X-Git-Url: https://git.artsoft.org/?p=rocksndiamonds.git;a=blobdiff_plain;f=src%2Fgame.c;h=7f98027c8fd1eab482f50346680d6d6fc4ddebbc;hp=57c7b87326383a566c1e09974e3d4d1aafa928e8;hb=f78f30b84a0345ea31b30c5bd95e338c9d9ebd4b;hpb=f13a8935ca1a7eeb3406d02f49b2df1490504017

diff --git a/src/game.c b/src/game.c
index 57c7b873..7f98027c 100644
--- a/src/game.c
+++ b/src/game.c
@@ -15,6 +15,7 @@
 #include "init.h"
 #include "tools.h"
 #include "screens.h"
+#include "events.h"
 #include "files.h"
 #include "tape.h"
 #include "network.h"
@@ -970,13 +971,16 @@ static struct GamePanelControlInfo game_panel_controls[] =
 #define GAME_CTRL_ID_STOP		0
 #define GAME_CTRL_ID_PAUSE		1
 #define GAME_CTRL_ID_PLAY		2
-#define SOUND_CTRL_ID_MUSIC		3
-#define SOUND_CTRL_ID_LOOPS		4
-#define SOUND_CTRL_ID_SIMPLE		5
-#define GAME_CTRL_ID_SAVE		6
+#define GAME_CTRL_ID_UNDO		3
+#define GAME_CTRL_ID_REDO		4
+#define GAME_CTRL_ID_SAVE		5
+#define GAME_CTRL_ID_PAUSE2		6
 #define GAME_CTRL_ID_LOAD		7
+#define SOUND_CTRL_ID_MUSIC		8
+#define SOUND_CTRL_ID_LOOPS		9
+#define SOUND_CTRL_ID_SIMPLE		10
 
-#define NUM_GAME_BUTTONS		8
+#define NUM_GAME_BUTTONS		11
 
 
 /* forward declaration for internal use */
@@ -1945,7 +1949,7 @@ static void InitField(int x, int y, boolean init_game)
     CheckTriggeredElementChange(x, y, element, CE_CREATION_OF_X);
 }
 
-static inline void InitField_WithBug1(int x, int y, boolean init_game)
+inline static void InitField_WithBug1(int x, int y, boolean init_game)
 {
   InitField(x, y, init_game);
 
@@ -1955,7 +1959,7 @@ static inline void InitField_WithBug1(int x, int y, boolean init_game)
     InitMovDir(x, y);
 }
 
-static inline void InitField_WithBug2(int x, int y, boolean init_game)
+inline static void InitField_WithBug2(int x, int y, boolean init_game)
 {
   int old_element = Feld[x][y];
 
@@ -3031,6 +3035,19 @@ static void InitGameEngine()
      setup.scroll_delay                   ? setup.scroll_delay_value       : 0);
   game.scroll_delay_value =
     MIN(MAX(MIN_SCROLL_DELAY, game.scroll_delay_value), MAX_SCROLL_DELAY);
+
+  /* ---------- initialize game engine snapshots ---------------------------- */
+  for (i = 0; i < MAX_PLAYERS; i++)
+    game.snapshot.last_action[i] = 0;
+  game.snapshot.changed_action = FALSE;
+  game.snapshot.collected_item = FALSE;
+  game.snapshot.mode =
+    (strEqual(setup.engine_snapshot_mode, STR_SNAPSHOT_MODE_EVERY_STEP) ?
+     SNAPSHOT_MODE_EVERY_STEP :
+     strEqual(setup.engine_snapshot_mode, STR_SNAPSHOT_MODE_EVERY_MOVE) ?
+     SNAPSHOT_MODE_EVERY_MOVE :
+     strEqual(setup.engine_snapshot_mode, STR_SNAPSHOT_MODE_EVERY_COLLECT) ?
+     SNAPSHOT_MODE_EVERY_COLLECT : SNAPSHOT_MODE_OFF);
 }
 
 int get_num_special_action(int element, int action_first, int action_last)
@@ -3069,6 +3086,7 @@ void InitGame()
 {
   int full_lev_fieldx = lev_fieldx + (BorderElement != EL_EMPTY ? 2 : 0);
   int full_lev_fieldy = lev_fieldy + (BorderElement != EL_EMPTY ? 2 : 0);
+  int fade_mask = REDRAW_FIELD;
 
   boolean emulate_bd = TRUE;	/* unless non-BOULDERDASH elements found */
   boolean emulate_sb = TRUE;	/* unless non-SOKOBAN     elements found */
@@ -3076,22 +3094,30 @@ void InitGame()
   int initial_move_dir = MV_DOWN;
   int i, j, x, y;
 
-  game_status = GAME_MODE_PLAYING;
+  // required here to update video display before fading (FIX THIS)
+  DrawMaskedBorder(REDRAW_DOOR_2);
 
-  StopAnimation();
+  game_status = GAME_MODE_PLAYING;
 
   if (!game.restart_level)
     CloseDoor(DOOR_CLOSE_1);
 
+  /* needed if different viewport properties defined for playing */
+  ChangeViewportPropertiesIfNeeded();
+
   if (level_editor_test_game)
     FadeSkipNextFadeIn();
   else
     FadeSetEnterScreen();
 
-  FadeOut(REDRAW_FIELD);
+  if (CheckIfGlobalBorderHasChanged())
+    fade_mask = REDRAW_ALL;
 
-  /* needed if different viewport properties defined for playing */
-  ChangeViewportPropertiesIfNeeded();
+  FadeOut(fade_mask);
+
+  OpenDoor(GetDoorState() | DOOR_NO_DELAY | DOOR_FORCE_REDRAW);
+
+  ClearField();
 
   DrawCompleteVideoDisplay();
 
@@ -3903,11 +3929,11 @@ void InitGame()
 
   /* blit playfield from scroll buffer to normal back buffer for fading in */
   BlitScreenToBitmap(backbuffer);
-
-  redraw_mask |= REDRAW_FROM_BACKBUFFER;
   /* !!! FIX THIS (END) !!! */
 
-  FadeIn(REDRAW_FIELD);
+  DrawMaskedBorder(fade_mask);
+
+  FadeIn(fade_mask);
 
 #if 1
   // full screen redraw is required at this point in the following cases:
@@ -3936,9 +3962,14 @@ void InitGame()
   {
     UnmapGameButtons();
     UnmapTapeButtons();
+
+    FreeGameButtons();
+    CreateGameButtons();
+
     game_gadget[SOUND_CTRL_ID_MUSIC]->checked = setup.sound_music;
     game_gadget[SOUND_CTRL_ID_LOOPS]->checked = setup.sound_loops;
     game_gadget[SOUND_CTRL_ID_SIMPLE]->checked = setup.sound_simple;
+
     MapGameButtons();
     MapTapeButtons();
 
@@ -3991,6 +4022,8 @@ void InitGame()
   }
 
   game.restart_level = FALSE;
+
+  SaveEngineSnapshotToListInitial();
 }
 
 void UpdateEngineValues(int actual_scroll_x, int actual_scroll_y)
@@ -4377,29 +4410,30 @@ void GameEnd()
 
   local_player->LevelSolved_GameEnd = TRUE;
 
-  CloseDoor(DOOR_CLOSE_1);
+  if (!global.use_envelope_request)
+    CloseDoor(DOOR_CLOSE_1);
 
   if (local_player->LevelSolved_SaveTape)
   {
     SaveTapeChecked(tape.level_nr);	/* ask to save tape */
   }
 
+  CloseDoor(DOOR_CLOSE_ALL);
+
   if (level_editor_test_game)
   {
     game_status = GAME_MODE_MAIN;
 
-    DrawAndFadeInMainMenu(REDRAW_FIELD);
+    DrawMainMenu();
 
     return;
   }
 
   if (!local_player->LevelSolved_SaveScore)
   {
-    FadeOut(REDRAW_FIELD);
-
     game_status = GAME_MODE_MAIN;
 
-    DrawAndFadeInMainMenu(REDRAW_FIELD);
+    DrawMainMenu();
 
     return;
   }
@@ -4428,8 +4462,6 @@ void GameEnd()
   }
   else
   {
-    FadeOut(REDRAW_FIELD);
-
     game_status = GAME_MODE_MAIN;
 
     if (raise_level)
@@ -4438,7 +4470,7 @@ void GameEnd()
       TapeErase();
     }
 
-    DrawAndFadeInMainMenu(REDRAW_FIELD);
+    DrawMainMenu();
   }
 }
 
@@ -4862,164 +4894,101 @@ void DrawRelocateScreen(int old_x, int old_y, int x, int y, int move_dir,
   boolean no_delay = (tape.warp_forward);
   int frame_delay_value = (ffwd_delay ? FfwdFrameDelay : GameFrameDelay);
   int wait_delay_value = (no_delay ? 0 : frame_delay_value);
+  int new_scroll_x, new_scroll_y;
 
-  if (quick_relocation)
+  if (level.lazy_relocation && IN_VIS_FIELD(SCREENX(x), SCREENY(y)))
   {
-    if (!IN_VIS_FIELD(SCREENX(x), SCREENY(y)) || center_screen)
-    {
-      if (!level.shifted_relocation || center_screen)
-      {
-	/* quick relocation (without scrolling), with centering of screen */
-
-	scroll_x = (x < SBX_Left  + MIDPOSX ? SBX_Left :
-		    x > SBX_Right + MIDPOSX ? SBX_Right :
-		    x - MIDPOSX);
-
-	scroll_y = (y < SBY_Upper + MIDPOSY ? SBY_Upper :
-		    y > SBY_Lower + MIDPOSY ? SBY_Lower :
-		    y - MIDPOSY);
-      }
-      else
-      {
-	/* quick relocation (without scrolling), but do not center screen */
+    /* case 1: quick relocation inside visible screen (without scrolling) */
 
-	int center_scroll_x = (old_x < SBX_Left  + MIDPOSX ? SBX_Left :
-			       old_x > SBX_Right + MIDPOSX ? SBX_Right :
-			       old_x - MIDPOSX);
+    RedrawPlayfield();
 
-	int center_scroll_y = (old_y < SBY_Upper + MIDPOSY ? SBY_Upper :
-			       old_y > SBY_Lower + MIDPOSY ? SBY_Lower :
-			       old_y - MIDPOSY);
-
-	int offset_x = x + (scroll_x - center_scroll_x);
-	int offset_y = y + (scroll_y - center_scroll_y);
-
-	scroll_x = (offset_x < SBX_Left  + MIDPOSX ? SBX_Left :
-		    offset_x > SBX_Right + MIDPOSX ? SBX_Right :
-		    offset_x - MIDPOSX);
+    return;
+  }
 
-	scroll_y = (offset_y < SBY_Upper + MIDPOSY ? SBY_Upper :
-		    offset_y > SBY_Lower + MIDPOSY ? SBY_Lower :
-		    offset_y - MIDPOSY);
-      }
-    }
-    else
-    {
-      if (!level.shifted_relocation || center_screen)
-      {
-	/* quick relocation (without scrolling), with centering of screen */
+  if (!level.shifted_relocation || center_screen)
+  {
+    /* relocation _with_ centering of screen */
 
-	scroll_x = (x < SBX_Left  + MIDPOSX ? SBX_Left :
+    new_scroll_x = (x < SBX_Left  + MIDPOSX ? SBX_Left :
 		    x > SBX_Right + MIDPOSX ? SBX_Right :
 		    x - MIDPOSX);
 
-	scroll_y = (y < SBY_Upper + MIDPOSY ? SBY_Upper :
+    new_scroll_y = (y < SBY_Upper + MIDPOSY ? SBY_Upper :
 		    y > SBY_Lower + MIDPOSY ? SBY_Lower :
 		    y - MIDPOSY);
-      }
-      else
-      {
-	/* quick relocation (without scrolling), but do not center screen */
+  }
+  else
+  {
+    /* relocation _without_ centering of screen */
 
-	int center_scroll_x = (old_x < SBX_Left  + MIDPOSX ? SBX_Left :
-			       old_x > SBX_Right + MIDPOSX ? SBX_Right :
-			       old_x - MIDPOSX);
+    int center_scroll_x = (old_x < SBX_Left  + MIDPOSX ? SBX_Left :
+			   old_x > SBX_Right + MIDPOSX ? SBX_Right :
+			   old_x - MIDPOSX);
 
-	int center_scroll_y = (old_y < SBY_Upper + MIDPOSY ? SBY_Upper :
-			       old_y > SBY_Lower + MIDPOSY ? SBY_Lower :
-			       old_y - MIDPOSY);
+    int center_scroll_y = (old_y < SBY_Upper + MIDPOSY ? SBY_Upper :
+			   old_y > SBY_Lower + MIDPOSY ? SBY_Lower :
+			   old_y - MIDPOSY);
 
-	int offset_x = x + (scroll_x - center_scroll_x);
-	int offset_y = y + (scroll_y - center_scroll_y);
+    int offset_x = x + (scroll_x - center_scroll_x);
+    int offset_y = y + (scroll_y - center_scroll_y);
 
-	scroll_x = (offset_x < SBX_Left  + MIDPOSX ? SBX_Left :
+    new_scroll_x = (offset_x < SBX_Left  + MIDPOSX ? SBX_Left :
 		    offset_x > SBX_Right + MIDPOSX ? SBX_Right :
 		    offset_x - MIDPOSX);
 
-	scroll_y = (offset_y < SBY_Upper + MIDPOSY ? SBY_Upper :
+    new_scroll_y = (offset_y < SBY_Upper + MIDPOSY ? SBY_Upper :
 		    offset_y > SBY_Lower + MIDPOSY ? SBY_Lower :
 		    offset_y - MIDPOSY);
-      }
-    }
-
-    RedrawPlayfield(TRUE, 0,0,0,0);
   }
-  else
-  {
-    int scroll_xx, scroll_yy;
-
-    if (!level.shifted_relocation || center_screen)
-    {
-      /* visible relocation (with scrolling), with centering of screen */
-
-      scroll_xx = (x < SBX_Left  + MIDPOSX ? SBX_Left :
-		   x > SBX_Right + MIDPOSX ? SBX_Right :
-		   x - MIDPOSX);
-
-      scroll_yy = (y < SBY_Upper + MIDPOSY ? SBY_Upper :
-		   y > SBY_Lower + MIDPOSY ? SBY_Lower :
-		   y - MIDPOSY);
-    }
-    else
-    {
-      /* visible relocation (with scrolling), but do not center screen */
-
-      int center_scroll_x = (old_x < SBX_Left  + MIDPOSX ? SBX_Left :
-			     old_x > SBX_Right + MIDPOSX ? SBX_Right :
-			     old_x - MIDPOSX);
-
-      int center_scroll_y = (old_y < SBY_Upper + MIDPOSY ? SBY_Upper :
-			     old_y > SBY_Lower + MIDPOSY ? SBY_Lower :
-			     old_y - MIDPOSY);
 
-      int offset_x = x + (scroll_x - center_scroll_x);
-      int offset_y = y + (scroll_y - center_scroll_y);
+  if (quick_relocation)
+  {
+    /* case 2: quick relocation (redraw without visible scrolling) */
 
-      scroll_xx = (offset_x < SBX_Left  + MIDPOSX ? SBX_Left :
-		   offset_x > SBX_Right + MIDPOSX ? SBX_Right :
-		   offset_x - MIDPOSX);
+    scroll_x = new_scroll_x;
+    scroll_y = new_scroll_y;
 
-      scroll_yy = (offset_y < SBY_Upper + MIDPOSY ? SBY_Upper :
-		   offset_y > SBY_Lower + MIDPOSY ? SBY_Lower :
-		   offset_y - MIDPOSY);
-    }
+    RedrawPlayfield();
 
+    return;
+  }
 
-    ScrollScreen(NULL, SCROLL_GO_ON);	/* scroll last frame to full tile */
+  /* case 3: visible relocation (with scrolling to new position) */
 
-    while (scroll_x != scroll_xx || scroll_y != scroll_yy)
-    {
-      int dx = 0, dy = 0;
-      int fx = FX, fy = FY;
+  ScrollScreen(NULL, SCROLL_GO_ON);	/* scroll last frame to full tile */
 
-      dx = (scroll_xx < scroll_x ? +1 : scroll_xx > scroll_x ? -1 : 0);
-      dy = (scroll_yy < scroll_y ? +1 : scroll_yy > scroll_y ? -1 : 0);
+  while (scroll_x != new_scroll_x || scroll_y != new_scroll_y)
+  {
+    int dx = 0, dy = 0;
+    int fx = FX, fy = FY;
 
-      if (dx == 0 && dy == 0)		/* no scrolling needed at all */
-	break;
+    dx = (new_scroll_x < scroll_x ? +1 : new_scroll_x > scroll_x ? -1 : 0);
+    dy = (new_scroll_y < scroll_y ? +1 : new_scroll_y > scroll_y ? -1 : 0);
 
-      scroll_x -= dx;
-      scroll_y -= dy;
+    if (dx == 0 && dy == 0)		/* no scrolling needed at all */
+      break;
 
-      fx += dx * TILEX / 2;
-      fy += dy * TILEY / 2;
+    scroll_x -= dx;
+    scroll_y -= dy;
 
-      ScrollLevel(dx, dy);
-      DrawAllPlayers();
+    fx += dx * TILEX / 2;
+    fy += dy * TILEY / 2;
 
-      /* scroll in two steps of half tile size to make things smoother */
-      BlitBitmap(drawto_field, window, fx, fy, SXSIZE, SYSIZE, SX, SY);
-      Delay(wait_delay_value);
+    ScrollLevel(dx, dy);
+    DrawAllPlayers();
 
-      /* scroll second step to align at full tile size */
-      BackToFront();
-      Delay(wait_delay_value);
-    }
+    /* scroll in two steps of half tile size to make things smoother */
+    BlitBitmap(drawto_field, window, fx, fy, SXSIZE, SYSIZE, SX, SY);
+    Delay(wait_delay_value);
 
-    DrawAllPlayers();
+    /* scroll second step to align at full tile size */
     BackToFront();
     Delay(wait_delay_value);
   }
+
+  DrawAllPlayers();
+  BackToFront();
+  Delay(wait_delay_value);
 }
 
 void RelocatePlayer(int jx, int jy, int el_player_raw)
@@ -9528,6 +9497,8 @@ static void ExecuteCustomElementAction(int x, int y, int element, int page)
     {
       local_player->gems_still_needed = action_arg_number_new;
 
+      game.snapshot.collected_item = TRUE;
+
       game_panel_controls[GAME_PANEL_GEMS].value =
 	local_player->gems_still_needed;
 
@@ -10216,9 +10187,50 @@ static void HandleElementChange(int x, int y, int page)
     {
       /* !!! not clear why graphic animation should be reset at all here !!! */
       /* !!! UPDATE: but is needed for correct Snake Bite tail animation !!! */
+      /* !!! SOLUTION: do not reset if graphics engine set to 4 or above !!! */
+
+      /*
+	GRAPHICAL BUG ADDRESSED BY CHECKING GRAPHICS ENGINE VERSION:
+
+	When using an animation frame delay of 1 (this only happens with
+	"sp_zonk.moving.left/right" in the classic graphics), the default
+	(non-moving) animation shows wrong animation frames (while the
+	moving animation, like "sp_zonk.moving.left/right", is correct,
+	so this graphical bug never shows up with the classic graphics).
+	For an animation with 4 frames, this causes wrong frames 0,0,1,2
+	be drawn instead of the correct frames 0,1,2,3. This is caused by
+	"GfxFrame[][]" being reset *twice* (in two successive frames) after
+	an element change: First when the change delay ("ChangeDelay[][]")
+	counter has reached zero after decrementing, then a second time in
+	the next frame (after "GfxFrame[][]" was already incremented) when
+	"ChangeDelay[][]" is reset to the initial delay value again.
+
+	This causes frame 0 to be drawn twice, while the last frame won't
+	be drawn anymore, resulting in the wrong frame sequence 0,0,1,2.
+
+	As some animations may already be cleverly designed around this bug
+	(at least the "Snake Bite" snake tail animation does this), it cannot
+	simply be fixed here without breaking such existing animations.
+	Unfortunately, it cannot easily be detected if a graphics set was
+	designed "before" or "after" the bug was fixed. As a workaround,
+	a new graphics set option "game.graphics_engine_version" was added
+	to be able to specify the game's major release version for which the
+	graphics set was designed, which can then be used to decide if the
+	bugfix should be used (version 4 and above) or not (version 3 or
+	below, or if no version was specified at all, as with old sets).
+
+	(The wrong/fixed animation frames can be tested with the test level set
+	"test_gfxframe" and level "000", which contains a specially prepared
+	custom element at level position (x/y) == (11/9) which uses the zonk
+	animation mentioned above. Using "game.graphics_engine_version: 4"
+	fixes the wrong animation frames, showing the correct frames 0,1,2,3.
+	This can also be seen from the debug output for this test element.)
+      */
+
       /* when a custom element is about to change (for example by change delay),
 	 do not reset graphic animation when the custom element is moving */
-      if (!IS_MOVING(x, y))
+      if (game.graphics_engine_version < 4 &&
+	  !IS_MOVING(x, y))
       {
 	ResetGfxAnimation(x, y);
 	ResetRandomAnimationValue(x, y);
@@ -10668,6 +10680,37 @@ static void SetPlayerWaiting(struct PlayerInfo *player, boolean is_waiting)
   }
 }
 
+static void CheckSaveEngineSnapshot(struct PlayerInfo *player)
+{
+  static boolean player_was_moving = FALSE;
+  static boolean player_was_snapping = FALSE;
+  static boolean player_was_dropping = FALSE;
+
+  if ((!player->is_moving  && player_was_moving) ||
+      (player->MovPos == 0 && player_was_moving) ||
+      (player->is_snapping && !player_was_snapping) ||
+      (player->is_dropping && !player_was_dropping))
+  {
+    if (!SaveEngineSnapshotToList())
+      return;
+
+    player_was_moving = FALSE;
+    player_was_snapping = TRUE;
+    player_was_dropping = TRUE;
+  }
+  else
+  {
+    if (player->is_moving)
+      player_was_moving = TRUE;
+
+    if (!player->is_snapping)
+      player_was_snapping = FALSE;
+
+    if (!player->is_dropping)
+      player_was_dropping = FALSE;
+  }
+}
+
 static void CheckSingleStepMode(struct PlayerInfo *player)
 {
   if (tape.single_step && tape.recording && !tape.pausing)
@@ -10680,6 +10723,8 @@ static void CheckSingleStepMode(struct PlayerInfo *player)
       SnapField(player, 0, 0);			/* stop snapping */
     }
   }
+
+  CheckSaveEngineSnapshot(player);
 }
 
 static byte PlayerActions(struct PlayerInfo *player, byte player_action)
@@ -10987,9 +11032,18 @@ void GameActions()
   if (tape.playing && tape.warp_forward && !tape.pausing)
     game_frame_delay_value = 0;
 
+#if 0
+  /* ---------- main game synchronization point ---------- */
+
+  int skip = WaitUntilDelayReached(&game_frame_delay, game_frame_delay_value);
+
+  printf("::: skip == %d\n", skip);
+
+#else
   /* ---------- main game synchronization point ---------- */
 
   WaitUntilDelayReached(&game_frame_delay, game_frame_delay_value);
+#endif
 
   if (network_playing && !network_player_action_received)
   {
@@ -11113,6 +11167,21 @@ void GameActions()
 #endif
 #endif
 
+  for (i = 0; i < MAX_PLAYERS; i++)
+  {
+    // allow engine snapshot in case of changed movement attempt
+    if ((game.snapshot.last_action[i] & KEY_MOTION) !=
+	(stored_player[i].effective_action & KEY_MOTION))
+      game.snapshot.changed_action = TRUE;
+
+    // allow engine snapshot in case of snapping/dropping attempt
+    if ((game.snapshot.last_action[i] & KEY_BUTTON) == 0 &&
+	(stored_player[i].effective_action & KEY_BUTTON) != 0)
+      game.snapshot.changed_action = TRUE;
+
+    game.snapshot.last_action[i] = stored_player[i].effective_action;
+  }
+
   if (level.game_engine_type == GAME_ENGINE_TYPE_EM)
   {
     GameActions_EM_Main();
@@ -11123,7 +11192,32 @@ void GameActions()
   }
   else
   {
-    GameActions_RND();
+    GameActions_RND_Main();
+  }
+
+  BlitScreenToBitmap(backbuffer);
+
+  CheckLevelTime();
+
+  AdvanceFrameAndPlayerCounters(-1);	/* advance counters for all players */
+
+  if (options.debug)			/* calculate frames per second */
+  {
+    static unsigned int fps_counter = 0;
+    static int fps_frames = 0;
+    unsigned int fps_delay_ms = Counter() - fps_counter;
+
+    fps_frames++;
+
+    if (fps_delay_ms >= 500)	/* calculate fps every 0.5 seconds */
+    {
+      global.frames_per_second = 1000 * (float)fps_frames / fps_delay_ms;
+
+      fps_frames = 0;
+      fps_counter = Counter();
+    }
+
+    redraw_mask |= REDRAW_FPS;
   }
 }
 
@@ -11137,10 +11231,6 @@ void GameActions_EM_Main()
     effective_action[i] = stored_player[i].effective_action;
 
   GameActions_EM(effective_action, warp_mode);
-
-  CheckLevelTime();
-
-  AdvanceFrameAndPlayerCounters(-1);	/* advance counters for all players */
 }
 
 void GameActions_SP_Main()
@@ -11153,10 +11243,11 @@ void GameActions_SP_Main()
     effective_action[i] = stored_player[i].effective_action;
 
   GameActions_SP(effective_action, warp_mode);
+}
 
-  CheckLevelTime();
-
-  AdvanceFrameAndPlayerCounters(-1);	/* advance counters for all players */
+void GameActions_RND_Main()
+{
+  GameActions_RND();
 }
 
 void GameActions_RND()
@@ -11658,32 +11749,9 @@ void GameActions_RND()
   }
 #endif
 
-  CheckLevelTime();
-
   DrawAllPlayers();
   PlayAllPlayersSound();
 
-  if (options.debug)			/* calculate frames per second */
-  {
-    static unsigned int fps_counter = 0;
-    static int fps_frames = 0;
-    unsigned int fps_delay_ms = Counter() - fps_counter;
-
-    fps_frames++;
-
-    if (fps_delay_ms >= 500)	/* calculate fps every 0.5 seconds */
-    {
-      global.frames_per_second = 1000 * (float)fps_frames / fps_delay_ms;
-
-      fps_frames = 0;
-      fps_counter = Counter();
-    }
-
-    redraw_mask |= REDRAW_FPS;
-  }
-
-  AdvanceFrameAndPlayerCounters(-1);	/* advance counters for all players */
-
   if (local_player->show_envelope != 0 && local_player->MovPos == 0)
   {
     ShowEnvelope(local_player->show_envelope - EL_ENVELOPE_1);
@@ -11737,16 +11805,16 @@ static boolean AllPlayersInVisibleScreen()
 
 void ScrollLevel(int dx, int dy)
 {
-  int softscroll_offset = (setup.soft_scrolling ? 2 * TILEX_VAR : 0);
+  int scroll_offset = 2 * TILEX_VAR;
   int x, y;
 
   BlitBitmap(drawto_field, drawto_field,
-	     FX + TILEX_VAR * (dx == -1) - softscroll_offset,
-	     FY + TILEY_VAR * (dy == -1) - softscroll_offset,
-	     SXSIZE - TILEX_VAR * (dx != 0) + 2 * softscroll_offset,
-	     SYSIZE - TILEY_VAR * (dy != 0) + 2 * softscroll_offset,
-	     FX + TILEX_VAR * (dx == 1) - softscroll_offset,
-	     FY + TILEY_VAR * (dy == 1) - softscroll_offset);
+	     FX + TILEX_VAR * (dx == -1) - scroll_offset,
+	     FY + TILEY_VAR * (dy == -1) - scroll_offset,
+	     SXSIZE - TILEX_VAR * (dx != 0) + 2 * scroll_offset,
+	     SYSIZE - TILEY_VAR * (dy != 0) + 2 * scroll_offset,
+	     FX + TILEX_VAR * (dx == 1) - scroll_offset,
+	     FY + TILEY_VAR * (dy == 1) - scroll_offset);
 
   if (dx != 0)
   {
@@ -12308,6 +12376,9 @@ void ScrollPlayer(struct PlayerInfo *player, int mode)
     if (tape.single_step && tape.recording && !tape.pausing &&
 	!player->programmed_action)
       TapeTogglePause(TAPE_TOGGLE_AUTOMATIC);
+
+    if (!player->programmed_action)
+      CheckSaveEngineSnapshot(player);
   }
 }
 
@@ -13392,6 +13463,8 @@ static int DigField(struct PlayerInfo *player,
       if (local_player->gems_still_needed < 0)
 	local_player->gems_still_needed = 0;
 
+      game.snapshot.collected_item = TRUE;
+
       game_panel_controls[GAME_PANEL_GEMS].value = local_player->gems_still_needed;
 
       DisplayGameControlValues();
@@ -13590,9 +13663,16 @@ static int DigField(struct PlayerInfo *player,
       SCAN_PLAYFIELD(xx, yy)
       {
 	if (Feld[xx][yy] == EL_SP_DISK_YELLOW)
+	{
 	  Bang(xx, yy);
+	}
 	else if (Feld[xx][yy] == EL_SP_TERMINAL)
+	{
 	  Feld[xx][yy] = EL_SP_TERMINAL_ACTIVE;
+
+	  ResetGfxAnimation(xx, yy);
+	  TEST_DrawLevelField(xx, yy);
+	}
       }
     }
     else if (IS_BELT_SWITCH(element))
@@ -14384,19 +14464,11 @@ void RequestQuitGameExt(boolean skip_request, boolean quick_quit, char *message)
 #endif
     {
       if (quick_quit)
-      {
 	FadeSkipNextFadeIn();
 
-	game_status = GAME_MODE_MAIN;
-
-	DrawAndFadeInMainMenu(REDRAW_FIELD);
-      }
-      else
-      {
-	game_status = GAME_MODE_MAIN;
+      game_status = GAME_MODE_MAIN;
 
-	DrawAndFadeInMainMenu(REDRAW_FIELD);
-      }
+      DrawMainMenu();
     }
   }
   else		/* continue playing the game */
@@ -14551,22 +14623,22 @@ static void LoadEngineSnapshotValues_RND()
   }
 }
 
-void FreeEngineSnapshot()
+void FreeEngineSnapshotSingle()
 {
-  FreeEngineSnapshotBuffers();
+  FreeSnapshotSingle();
 
   setString(&snapshot_level_identifier, NULL);
   snapshot_level_nr = -1;
 }
 
-void SaveEngineSnapshot()
+void FreeEngineSnapshotList()
 {
-  /* do not save snapshots from editor */
-  if (level_editor_test_game)
-    return;
+  FreeSnapshotList();
+}
 
-  /* free previous snapshot buffers, if needed */
-  FreeEngineSnapshotBuffers();
+ListNode *SaveEngineSnapshotBuffers()
+{
+  ListNode *buffers = NULL;
 
   /* copy some special values to a structure better suited for the snapshot */
 
@@ -14575,87 +14647,82 @@ void SaveEngineSnapshot()
   if (level.game_engine_type == GAME_ENGINE_TYPE_EM)
     SaveEngineSnapshotValues_EM();
   if (level.game_engine_type == GAME_ENGINE_TYPE_SP)
-    SaveEngineSnapshotValues_SP();
+    SaveEngineSnapshotValues_SP(&buffers);
 
   /* save values stored in special snapshot structure */
 
   if (level.game_engine_type == GAME_ENGINE_TYPE_RND)
-    SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(engine_snapshot_rnd));
+    SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(engine_snapshot_rnd));
   if (level.game_engine_type == GAME_ENGINE_TYPE_EM)
-    SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(engine_snapshot_em));
+    SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(engine_snapshot_em));
   if (level.game_engine_type == GAME_ENGINE_TYPE_SP)
-    SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(engine_snapshot_sp));
+    SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(engine_snapshot_sp));
 
   /* save further RND engine values */
 
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(stored_player));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(game));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(tape));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ZX));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ZY));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ExitX));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ExitY));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(FrameCounter));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(TimeFrames));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(TimePlayed));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(TimeLeft));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(TapeTime));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ScreenMovDir));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ScreenMovPos));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ScreenGfxPos));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ScrollStepSize));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(AllPlayersGone));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(AmoebaCnt));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(AmoebaCnt2));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(Feld));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(MovPos));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(MovDir));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(MovDelay));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ChangeDelay));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ChangePage));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(CustomValue));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(Store));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(Store2));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(StorePlayer));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(Back));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(AmoebaNr));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(WasJustMoving));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(WasJustFalling));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(CheckCollision));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(CheckImpact));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(Stop));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(Pushed));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ChangeCount));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ChangeEvent));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ExplodePhase));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ExplodeDelay));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(ExplodeField));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(RunnerVisit));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(PlayerVisit));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(GfxFrame));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(GfxRandom));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(GfxElement));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(GfxAction));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(GfxDir));
-
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(scroll_x));
-  SaveEngineSnapshotBuffer(ARGS_ADDRESS_AND_SIZEOF(scroll_y));
-
-  /* save level identification information */
-
-  setString(&snapshot_level_identifier, leveldir_current->identifier);
-  snapshot_level_nr = level_nr;
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(stored_player));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(game));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(tape));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ZX));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ZY));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ExitX));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ExitY));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(FrameCounter));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(TimeFrames));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(TimePlayed));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(TimeLeft));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(TapeTime));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ScreenMovDir));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ScreenMovPos));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ScreenGfxPos));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ScrollStepSize));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(AllPlayersGone));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(AmoebaCnt));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(AmoebaCnt2));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(Feld));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(MovPos));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(MovDir));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(MovDelay));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ChangeDelay));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ChangePage));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(CustomValue));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(Store));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(Store2));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(StorePlayer));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(Back));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(AmoebaNr));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(WasJustMoving));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(WasJustFalling));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(CheckCollision));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(CheckImpact));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(Stop));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(Pushed));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ChangeCount));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ChangeEvent));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ExplodePhase));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ExplodeDelay));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(ExplodeField));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(RunnerVisit));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(PlayerVisit));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(GfxFrame));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(GfxRandom));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(GfxElement));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(GfxAction));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(GfxDir));
+
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(scroll_x));
+  SaveSnapshotBuffer(&buffers, ARGS_ADDRESS_AND_SIZEOF(scroll_y));
 
 #if 0
   ListNode *node = engine_snapshot_list_rnd;
@@ -14670,14 +14737,62 @@ void SaveEngineSnapshot()
 
   printf("::: size of engine snapshot: %d bytes\n", num_bytes);
 #endif
+
+  return buffers;
+}
+
+void SaveEngineSnapshotSingle()
+{
+  ListNode *buffers = SaveEngineSnapshotBuffers();
+
+  /* finally save all snapshot buffers to single snapshot */
+  SaveSnapshotSingle(buffers);
+
+  /* save level identification information */
+  setString(&snapshot_level_identifier, leveldir_current->identifier);
+  snapshot_level_nr = level_nr;
+}
+
+static boolean SaveEngineSnapshotToListExt(boolean initial_snapshot)
+{
+  boolean save_snapshot =
+    (initial_snapshot ||
+     (game.snapshot.mode == SNAPSHOT_MODE_EVERY_STEP) ||
+     (game.snapshot.mode == SNAPSHOT_MODE_EVERY_MOVE &&
+      game.snapshot.changed_action) ||
+     (game.snapshot.mode == SNAPSHOT_MODE_EVERY_COLLECT &&
+      game.snapshot.collected_item));
+
+  game.snapshot.changed_action = FALSE;
+  game.snapshot.collected_item = FALSE;
+
+  if (game.snapshot.mode == SNAPSHOT_MODE_OFF ||
+      tape.quick_resume ||
+      !save_snapshot)
+    return FALSE;
+
+  ListNode *buffers = SaveEngineSnapshotBuffers();
+
+  /* finally save all snapshot buffers to snapshot list */
+  SaveSnapshotToList(buffers);
+
+  return TRUE;
 }
 
-void LoadEngineSnapshot()
+boolean SaveEngineSnapshotToList()
 {
-  /* restore generically stored snapshot buffers */
+  return SaveEngineSnapshotToListExt(FALSE);
+}
 
-  LoadEngineSnapshotBuffers();
+void SaveEngineSnapshotToListInitial()
+{
+  FreeEngineSnapshotList();
 
+  SaveEngineSnapshotToListExt(TRUE);
+}
+
+void LoadEngineSnapshotValues()
+{
   /* restore special values from snapshot structure */
 
   if (level.game_engine_type == GAME_ENGINE_TYPE_RND)
@@ -14688,12 +14803,38 @@ void LoadEngineSnapshot()
     LoadEngineSnapshotValues_SP();
 }
 
-boolean CheckEngineSnapshot()
+void LoadEngineSnapshotSingle()
+{
+  LoadSnapshotSingle();
+
+  LoadEngineSnapshotValues();
+}
+
+void LoadEngineSnapshot_Undo(int steps)
+{
+  LoadSnapshotFromList_Older(steps);
+
+  LoadEngineSnapshotValues();
+}
+
+void LoadEngineSnapshot_Redo(int steps)
+{
+  LoadSnapshotFromList_Newer(steps);
+
+  LoadEngineSnapshotValues();
+}
+
+boolean CheckEngineSnapshotSingle()
 {
   return (strEqual(snapshot_level_identifier, leveldir_current->identifier) &&
 	  snapshot_level_nr == level_nr);
 }
 
+boolean CheckEngineSnapshotList()
+{
+  return CheckSnapshotList();
+}
+
 
 /* ---------- new game button stuff ---------------------------------------- */
 
@@ -14718,24 +14859,36 @@ static struct
     GAME_CTRL_ID_PLAY,			"play game"
   },
   {
-    IMG_GAME_BUTTON_GFX_SOUND_MUSIC,	&game.button.sound_music,
-    SOUND_CTRL_ID_MUSIC,		"background music on/off"
+    IMG_GAME_BUTTON_GFX_UNDO,		&game.button.undo,
+    GAME_CTRL_ID_UNDO,			"undo step"
   },
   {
-    IMG_GAME_BUTTON_GFX_SOUND_LOOPS,	&game.button.sound_loops,
-    SOUND_CTRL_ID_LOOPS,		"sound loops on/off"
-  },
-  {
-    IMG_GAME_BUTTON_GFX_SOUND_SIMPLE,	&game.button.sound_simple,
-    SOUND_CTRL_ID_SIMPLE,		"normal sounds on/off"
+    IMG_GAME_BUTTON_GFX_REDO,		&game.button.redo,
+    GAME_CTRL_ID_REDO,			"redo step"
   },
   {
     IMG_GAME_BUTTON_GFX_SAVE,		&game.button.save,
     GAME_CTRL_ID_SAVE,			"save game"
   },
+  {
+    IMG_GAME_BUTTON_GFX_PAUSE2,		&game.button.pause2,
+    GAME_CTRL_ID_PAUSE2,		"pause game"
+  },
   {
     IMG_GAME_BUTTON_GFX_LOAD,		&game.button.load,
     GAME_CTRL_ID_LOAD,			"load game"
+  },
+  {
+    IMG_GAME_BUTTON_GFX_SOUND_MUSIC,	&game.button.sound_music,
+    SOUND_CTRL_ID_MUSIC,		"background music on/off"
+  },
+  {
+    IMG_GAME_BUTTON_GFX_SOUND_LOOPS,	&game.button.sound_loops,
+    SOUND_CTRL_ID_LOOPS,		"sound loops on/off"
+  },
+  {
+    IMG_GAME_BUTTON_GFX_SOUND_SIMPLE,	&game.button.sound_simple,
+    SOUND_CTRL_ID_SIMPLE,		"normal sounds on/off"
   }
 };
 
@@ -14771,7 +14924,6 @@ void CreateGameButtons()
     }
 
     if (id == GAME_CTRL_ID_STOP ||
-	id == GAME_CTRL_ID_PAUSE ||
 	id == GAME_CTRL_ID_PLAY ||
 	id == GAME_CTRL_ID_SAVE ||
 	id == GAME_CTRL_ID_LOAD)
@@ -14780,6 +14932,13 @@ void CreateGameButtons()
       checked = FALSE;
       event_mask = GD_EVENT_RELEASED;
     }
+    else if (id == GAME_CTRL_ID_UNDO ||
+	     id == GAME_CTRL_ID_REDO)
+    {
+      button_type = GD_TYPE_NORMAL_BUTTON;
+      checked = FALSE;
+      event_mask = GD_EVENT_PRESSED | GD_EVENT_REPEATED;
+    }
     else
     {
       button_type = GD_TYPE_CHECK_BUTTON;
@@ -14823,12 +14982,69 @@ void FreeGameButtons()
     FreeGadget(game_gadget[i]);
 }
 
+static void MapGameButtonsAtSamePosition(int id)
+{
+  int i;
+
+  for (i = 0; i < NUM_GAME_BUTTONS; i++)
+    if (i != id &&
+	gamebutton_info[i].pos->x == gamebutton_info[id].pos->x &&
+	gamebutton_info[i].pos->y == gamebutton_info[id].pos->y)
+      MapGadget(game_gadget[i]);
+}
+
+static void UnmapGameButtonsAtSamePosition(int id)
+{
+  int i;
+
+  for (i = 0; i < NUM_GAME_BUTTONS; i++)
+    if (i != id &&
+	gamebutton_info[i].pos->x == gamebutton_info[id].pos->x &&
+	gamebutton_info[i].pos->y == gamebutton_info[id].pos->y)
+      UnmapGadget(game_gadget[i]);
+}
+
+void MapUndoRedoButtons()
+{
+  UnmapGameButtonsAtSamePosition(GAME_CTRL_ID_UNDO);
+  UnmapGameButtonsAtSamePosition(GAME_CTRL_ID_REDO);
+
+  MapGadget(game_gadget[GAME_CTRL_ID_UNDO]);
+  MapGadget(game_gadget[GAME_CTRL_ID_REDO]);
+}
+
+void UnmapUndoRedoButtons()
+{
+  UnmapGadget(game_gadget[GAME_CTRL_ID_UNDO]);
+  UnmapGadget(game_gadget[GAME_CTRL_ID_REDO]);
+
+  MapGameButtonsAtSamePosition(GAME_CTRL_ID_UNDO);
+  MapGameButtonsAtSamePosition(GAME_CTRL_ID_REDO);
+}
+
 void MapGameButtons()
 {
   int i;
 
   for (i = 0; i < NUM_GAME_BUTTONS; i++)
-    MapGadget(game_gadget[i]);
+    if (i != GAME_CTRL_ID_UNDO &&
+	i != GAME_CTRL_ID_REDO)
+      MapGadget(game_gadget[i]);
+
+  if (setup.show_snapshot_buttons)
+  {
+    UnmapGameButtonsAtSamePosition(GAME_CTRL_ID_SAVE);
+    UnmapGameButtonsAtSamePosition(GAME_CTRL_ID_PAUSE2);
+    UnmapGameButtonsAtSamePosition(GAME_CTRL_ID_LOAD);
+  }
+  else
+  {
+    UnmapGameButtonsAtSamePosition(GAME_CTRL_ID_STOP);
+    UnmapGameButtonsAtSamePosition(GAME_CTRL_ID_PAUSE);
+    UnmapGameButtonsAtSamePosition(GAME_CTRL_ID_PLAY);
+  }
+
+  RedrawGameButtons();
 }
 
 void UnmapGameButtons()
@@ -14850,8 +15066,48 @@ void RedrawGameButtons()
   redraw_mask &= ~REDRAW_ALL;
 }
 
-static void HandleGameButtonsExt(int id)
+void GameUndoRedoExt()
+{
+  ClearPlayerAction();
+
+  tape.pausing = TRUE;
+
+  RedrawPlayfield();
+  UpdateAndDisplayGameControlValues();
+
+  DrawCompleteVideoDisplay();
+  DrawVideoDisplay(VIDEO_STATE_TIME_ON, TapeTime);
+  DrawVideoDisplay(VIDEO_STATE_FRAME_ON, FrameCounter);
+  DrawVideoDisplay((tape.single_step ? VIDEO_STATE_1STEP_ON :
+		    VIDEO_STATE_1STEP_OFF), 0);
+
+  BackToFront();
+}
+
+void GameUndo(int steps)
 {
+  if (!CheckEngineSnapshotList())
+    return;
+
+  LoadEngineSnapshot_Undo(steps);
+
+  GameUndoRedoExt();
+}
+
+void GameRedo(int steps)
+{
+  if (!CheckEngineSnapshotList())
+    return;
+
+  LoadEngineSnapshot_Redo(steps);
+
+  GameUndoRedoExt();
+}
+
+static void HandleGameButtonsExt(int id, int button)
+{
+  static boolean game_undo_executed = FALSE;
+  int steps = BUTTON_STEPSIZE(button);
   boolean handle_game_buttons =
     (game_status == GAME_MODE_PLAYING ||
      (game_status == GAME_MODE_MAIN && tape.show_game_buttons));
@@ -14873,6 +15129,7 @@ static void HandleGameButtonsExt(int id)
       break;
 
     case GAME_CTRL_ID_PAUSE:
+    case GAME_CTRL_ID_PAUSE2:
       if (options.network && game_status == GAME_MODE_PLAYING)
       {
 #if defined(NETWORK_AVALIABLE)
@@ -14884,6 +15141,9 @@ static void HandleGameButtonsExt(int id)
       }
       else
 	TapeTogglePause(TAPE_TOGGLE_MANUAL);
+
+      game_undo_executed = FALSE;
+
       break;
 
     case GAME_CTRL_ID_PLAY:
@@ -14898,13 +15158,37 @@ static void HandleGameButtonsExt(int id)
 	  SendToServer_ContinuePlaying();
 	else
 #endif
-	{
-	  tape.pausing = FALSE;
-	  DrawVideoDisplay(VIDEO_STATE_PAUSE_OFF, 0);
-	}
+	  TapeTogglePause(TAPE_TOGGLE_MANUAL);
       }
       break;
 
+    case GAME_CTRL_ID_UNDO:
+      // Important: When using "save snapshot when collecting an item" mode,
+      // load last (current) snapshot for first "undo" after pressing "pause"
+      // (else the last-but-one snapshot would be loaded, because the snapshot
+      // pointer already points to the last snapshot when pressing "pause",
+      // which is fine for "every step/move" mode, but not for "every collect")
+      if (game.snapshot.mode == SNAPSHOT_MODE_EVERY_COLLECT &&
+	  !game_undo_executed)
+	steps--;
+
+      game_undo_executed = TRUE;
+
+      GameUndo(steps);
+      break;
+
+    case GAME_CTRL_ID_REDO:
+      GameRedo(steps);
+      break;
+
+    case GAME_CTRL_ID_SAVE:
+      TapeQuickSave();
+      break;
+
+    case GAME_CTRL_ID_LOAD:
+      TapeQuickLoad();
+      break;
+
     case SOUND_CTRL_ID_MUSIC:
       if (setup.sound_music)
       { 
@@ -14944,14 +15228,6 @@ static void HandleGameButtonsExt(int id)
       }
       break;
 
-    case GAME_CTRL_ID_SAVE:
-      TapeQuickSave();
-      break;
-
-    case GAME_CTRL_ID_LOAD:
-      TapeQuickLoad();
-      break;
-
     default:
       break;
   }
@@ -14959,7 +15235,7 @@ static void HandleGameButtonsExt(int id)
 
 static void HandleGameButtons(struct GadgetInfo *gi)
 {
-  HandleGameButtonsExt(gi->custom_id);
+  HandleGameButtonsExt(gi->custom_id, gi->event.button);
 }
 
 void HandleSoundButtonKeys(Key key)