diff --git a/TODO.txt b/TODO.txt
index a394ea5..5245503 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -1,5 +1,6 @@
 general:
 
+- Refactor.
 - Rewrite python scripts to C (faster, less bloat).
 - Try to recolor textures and give them a bit more of variety.
 - automatic tests: a frontend that will play the game, check the state, rendered
diff --git a/assets/level0.gif b/assets/level0.gif
index eb2a6af..85091cd 100644
Binary files a/assets/level0.gif and b/assets/level0.gif differ
diff --git a/assets/level5.gif b/assets/level5.gif
index 13f9363..056c250 100644
Binary files a/assets/level5.gif and b/assets/level5.gif differ
diff --git a/game.h b/game.h
index f9460f4..9aee511 100755
--- a/game.h
+++ b/game.h
@@ -969,7 +969,7 @@ void SFG_pixelFunc(RCL_PixelInfo *pixel)
 
   RCL_Unit screenX = pixel->position.x * SFG_RAYCASTING_SUBSAMPLE;
 
-  for (uint8_t i = 0; i < SFG_RAYCASTING_SUBSAMPLE; ++i)
+  for (int_fast8_t i = 0; i < SFG_RAYCASTING_SUBSAMPLE; ++i)
   {
     SFG_setGamePixel(screenX,pixel->position.y,color);
     screenX++;
@@ -3968,8 +3968,8 @@ void SFG_drawMap()
         }
       }
 
-      for (uint16_t k = 0; k < SFG_MAP_PIXEL_SIZE; ++k)
-        for (uint16_t l = 0; l < SFG_MAP_PIXEL_SIZE; ++l)
+      for (int_fast16_t k = 0; k < SFG_MAP_PIXEL_SIZE; ++k)
+        for (int_fast16_t l = 0; l < SFG_MAP_PIXEL_SIZE; ++l)
           SFG_setGamePixel(x + l, y + k,color);
 
       x += SFG_MAP_PIXEL_SIZE;
@@ -4084,11 +4084,11 @@ uint8_t SFG_drawNumber(
 */
 void SFG_drawIndicationBorder(uint16_t width, uint8_t color)
 {
-  for (uint16_t j = 0; j < width; ++j)
+  for (int_fast16_t j = 0; j < width; ++j)
   {
     uint16_t j2 = SFG_GAME_RESOLUTION_Y - 1 - j;
 
-    for (uint16_t i = 0; i < SFG_GAME_RESOLUTION_X; ++i)
+    for (int_fast16_t i = 0; i < SFG_GAME_RESOLUTION_X; ++i)
     {
       if ((i & 0x01) == (j & 0x01))
       {
@@ -4098,11 +4098,11 @@ void SFG_drawIndicationBorder(uint16_t width, uint8_t color)
     }
   }
 
-  for (uint16_t i = 0; i < width; ++i)
+  for (int_fast16_t i = 0; i < width; ++i)
   {
     uint16_t i2 = SFG_GAME_RESOLUTION_X - 1 - i;
 
-    for (uint16_t j = width; j < SFG_GAME_RESOLUTION_Y - width; ++j)
+    for (int_fast16_t j = width; j < SFG_GAME_RESOLUTION_Y - width; ++j)
     {
       if ((i & 0x01) == (j & 0x01))
       {
@@ -4421,7 +4421,7 @@ void SFG_draw()
   } 
   else
   { 
-    for (uint16_t i = 0; i < SFG_Z_BUFFER_SIZE; ++i)
+    for (int_fast16_t i = 0; i < SFG_Z_BUFFER_SIZE; ++i)
       SFG_game.zBuffer[i] = 255;
 
     int16_t weaponBobOffset = 0;
@@ -4464,7 +4464,7 @@ void SFG_draw()
     // draw sprites:
 
     // monster sprites:
-    for (uint16_t i = 0; i < SFG_currentLevel.monsterRecordCount; ++i)
+    for (int_fast16_t i = 0; i < SFG_currentLevel.monsterRecordCount; ++i)
     {
       SFG_MonsterRecord m = SFG_currentLevel.monsterRecords[i];
 
@@ -4510,7 +4510,7 @@ void SFG_draw()
     }
 
     // item sprites:
-    for (uint16_t i = 0; i < SFG_currentLevel.itemRecordCount; ++i)
+    for (int_fast16_t i = 0; i < SFG_currentLevel.itemRecordCount; ++i)
       if (SFG_currentLevel.itemRecords[i] & SFG_ITEM_RECORD_ACTIVE_MASK)
       {
         RCL_Vector2D worldPosition;
diff --git a/main_sdl.c b/main_sdl.c
index d552f94..2c147c1 100644
--- a/main_sdl.c
+++ b/main_sdl.c
@@ -28,10 +28,10 @@
 #define SFG_LOG(str) puts(str);
 
 //  #define SFG_START_LEVEL 6
-//  #define SFG_IMMORTAL 1
-//  #define SFG_UNLOCK_DOOR 1
+  #define SFG_IMMORTAL 1
+  #define SFG_UNLOCK_DOOR 1
 //  #define SFG_REVEAL_MAP 1
-  #define SFG_INFINITE_AMMO 1
+//  #define SFG_INFINITE_AMMO 1
 
 //  #define SFG_SCREEN_RESOLUTION_X 80
 //  #define SFG_SCREEN_RESOLUTION_Y 64
@@ -417,7 +417,11 @@ int main(int argc, char *argv[])
   audioSpec.freq = 8000;
   audioSpec.format = AUDIO_U16;
   audioSpec.channels = 1;
+#ifdef __EMSCRIPTEN__
   audioSpec.samples = 1024;
+#else
+  audioSpec.samples = 256;
+#endif
 
   if (SDL_OpenAudio(&audioSpec,NULL) < 0)
     puts("SDL: could not initialize audio");