diff --git a/assets.h b/assets.h
index e233eb1..0870721 100644
--- a/assets.h
+++ b/assets.h
@@ -1,12 +1,13 @@
 #ifndef _LCR_ASSETS_H
 #define _LCR_ASSETS_H
 
-/*
+/** @file assets.h
+
   Licar: assets
 
-  This file holds assets, resources and other bigger pieces of data that will be
-  compiled right into the executable. This is so that for a minimal version of
-  the game a filesystem is not needed.
+  This file holds assets, resources and other bigger pieces of data that are to
+  be compiled right into the executable. This is so that for a minimal version
+  of the game a filesystem is not required.
 
   NOTES:
   - All images are 64x64, stored in an indexed mode (8bits pery pixel), the
@@ -103,23 +104,23 @@ struct
   const uint8_t *image;
 } LCR_currentImage;
 
-/*
-  Font characters are kind of "segmented display" characters, encoded with 16
-  bits (each for one segment) like this (numbered from LSB):
-
-   __0__ __2__
-  |\12  |\13  |
- 1| \  5| \  9|
-  |  \  |  \  |
-  |__4\_|__6\_|
-  |\14  |\15  |
- 3| \  7| \ 11|
-  |  \  |  \  |
-  |__8\_|_10\_|
-*/
-
 uint16_t LCR_getFontChar(char c)
 {
+  /*
+    Font consists of kind of "segmented display" characters, encoded with 16
+    bits (each for one segment) like this (numbered from LSB):
+
+     __0__ __2__
+    |\12  |\13  |
+   1| \  5| \  9|
+    |  \  |  \  |
+    |__4\_|__6\_|
+    |\14  |\15  |
+   3| \  7| \ 11|
+    |  \  |  \  |
+    |__8\_|_10\_|
+  */
+
 #define _F(a,b,c,d,e,f,g,h,i,j) return (1 << a) | (1 << b) | (1 << c) | (1 <<\
   d) | (1 << e) | (1 << f) | (1 << g) | (1 << h) | (1 << i) | (1 << j); break;
 
diff --git a/audio.h b/audio.h
index cced836..845a86d 100644
--- a/audio.h
+++ b/audio.h
@@ -1,4 +1,8 @@
-/*
+#ifndef _LCR_AUDIO
+#define _LCR_AUDIO
+
+/** @file audio.h
+
   Licar audio
 
   This file implements the audio system. The module only computes audio samples
@@ -7,9 +11,6 @@
   file, left to be optionally loaded and played by the frontend).
 */
 
-#ifndef _LCR_AUDIO
-#define _LCR_AUDIO
-
 #define LCR_SOUND_NONE 0
 #define LCR_SOUND_CLICK 1
 #define LCR_SOUND_CRASH_SMALL 2
@@ -58,7 +59,7 @@ void LCR_audioSetEngineIntensity(uint8_t value)
 }
 
 /**
-  Tells the audio system to play certain sound (see the sound constants).
+  Tells the audio system to play a certain sound (see the sound constants).
 */
 void LCR_audioPlaySound(uint8_t sound)
 {
@@ -67,6 +68,16 @@ void LCR_audioPlaySound(uint8_t sound)
   LCR_audio.soundPlayedFrame = 0;
 }
 
+/**
+  Same as LCR_audioPlaySound, but only plays the sound if no other sound is
+  playing.
+*/
+void LCR_audioPlaySoundIfFree(uint8_t sound)
+{
+  if (LCR_audio.soundPlayed == LCR_SOUND_NONE)
+    LCR_audioPlaySound(sound);
+}
+
 uint8_t _LCR_audioNoise(void)
 {
   LCR_audio.noise = LCR_audio.noise * 32310901 + 37;
@@ -106,6 +117,16 @@ uint8_t LCR_audioGetNextSample(void)
       break;
     }
 
+    case LCR_SOUND_ACCELERATOR:
+      result = putchar(((LCR_audio.soundPlayedFrame * 14 +
+        (((LCR_audio.soundPlayedFrame >> 2) * (LCR_audio.soundPlayedFrame >> 6))
+        >> 4)) & 0x0f));
+
+      if (LCR_audio.soundPlayedFrame >= 4000)
+        LCR_audio.soundPlayed = LCR_SOUND_NONE;
+
+      break;
+
     case LCR_SOUND_CLICK:
     {
       int v = ((LCR_audio.soundPlayedFrame >> 6) *
diff --git a/game.h b/game.h
index 735b30e..1914740 100644
--- a/game.h
+++ b/game.h
@@ -1,7 +1,8 @@
 #ifndef _LCR_GAME_H
 #define _LCR_GAME_H
 
-/*
+/** @file game.h
+
   Licar: game module
 
   This file implements the backend of a complete, actually playable game with
@@ -1385,6 +1386,8 @@ LCR_replayOutputStr(_LCR_gameDataCharWrite);
       LCR_audioPlaySound(LCR_SOUND_CRASH_BIG);
       LCR_LOG2("crash (big)");
     }
+    else if (events & LCR_RACING_EVENT_ACCELERATOR)
+      LCR_audioPlaySoundIfFree(LCR_SOUND_ACCELERATOR);
 
     int engineIntensity = LCR_carSpeedKMH() * 2;
 
diff --git a/general.h b/general.h
index bef9b20..e0c62be 100644
--- a/general.h
+++ b/general.h
@@ -1,7 +1,8 @@
 #ifndef _LCR_GENERAL_H
 #define _LCR_GENERAL_H
 
-/*
+/** @file general.h
+
   Licar: general
 
   This file holds general definitions used by all modules.
diff --git a/map.h b/map.h
index 929ac36..ea2f21b 100644
--- a/map.h
+++ b/map.h
@@ -1,7 +1,8 @@
 #ifndef _LCR_MAP
 #define _LCR_MAP
 
-/*
+/** @file map.h
+
   Licar: map module
 
   This implements maps (i.e. tracks, levels, ...).
@@ -58,31 +59,29 @@
 
 #include "general.h"
 
-#define LCR_MAP_NAME_MAX_LEN          15   /**< Maximum map name length (without
-                                             terminating zero. */
-#define LCR_BLOCK_START_CHAR          ':'
+#define LCR_MAP_NAME_MAX_LEN        15   /**< Maximum map name length (without
+                                              terminating zero. */
+#define LCR_BLOCK_START_CHAR        ':'
 
 /** Maximum number of triangles of a block shape. */
 #define LCR_MAP_BLOCK_SHAPE_MAX_BYTES 80
 
-#define LCR_BLOCK_TRANSFORM_FLIP_H    0x10
-#define LCR_BLOCK_TRANSFORM_ROT_90    0x20
-#define LCR_BLOCK_TRANSFORM_ROT_180   0x40
-#define LCR_BLOCK_TRANSFORM_ROT_270   0x60
-#define LCR_BLOCK_TRANSFORM_FLIP_V    0x80
+#define LCR_BLOCK_TRANSFORM_FLIP_H  0x10
+#define LCR_BLOCK_TRANSFORM_ROT_90  0x20
+#define LCR_BLOCK_TRANSFORM_ROT_180 0x40
+#define LCR_BLOCK_TRANSFORM_ROT_270 0x60
+#define LCR_BLOCK_TRANSFORM_FLIP_V  0x80
 
-#define LCR_BLOCK_XYZ_TO_COORD(x,y,z) // ??? 
+#define LCR_MAP_BLOCK(t,x,y,z,m,r)  t,(uint8_t) (x | (y << 6)), \
+                                    (uint8_t) ((y >> 2) | (z << 4)), \
+                                    (uint8_t) ((z >> 4) | (m << 2) | (r))
 
-#define LCR_MAP_BLOCK(t,x,y,z,m,r)    t,(uint8_t) (x | (y << 6)), \
-                                      (uint8_t) ((y >> 2) | (z << 4)), \
-                                      (uint8_t) ((z >> 4) | (m << 2) | (r))
+#define LCR_BLOCK_SIZE              4    ///< size of map block, in bytes
 
-#define LCR_BLOCK_SIZE                4 ///< size of map block, in bytes
-
-#define LCR_BLOCK_MATERIAL_CONCRETE   0x00
-#define LCR_BLOCK_MATERIAL_GRASS      0x01
-#define LCR_BLOCK_MATERIAL_DIRT       0x02
-#define LCR_BLOCK_MATERIAL_ICE        0x03
+#define LCR_BLOCK_MATERIAL_CONCRETE 0x00
+#define LCR_BLOCK_MATERIAL_GRASS    0x01
+#define LCR_BLOCK_MATERIAL_DIRT     0x02
+#define LCR_BLOCK_MATERIAL_ICE      0x03
 
 // normal blocks:
 #define LCR_BLOCK_FULL              '='  ///< completely filled block
@@ -97,7 +96,7 @@
 #define LCR_BLOCK_RAMP_14           '_'  ///< plain ramp, 1/4 size
 #define LCR_BLOCK_RAMP_12_UP        '\'' ///< ramp, 1/2 size, elevated up
 #define LCR_BLOCK_RAMP_CORNER       'v'  ///< corner of a ramp
-#define LCR_BLOCK_RAMP_CURVED_PLAT  ']'  ///< curved ramp with top platgform
+#define LCR_BLOCK_RAMP_CURVED_PLAT  ']'  ///< curved ramp with top platform
 #define LCR_BLOCK_RAMP_CURVED       ')'  ///< curv. ramp without top platf.
 #define LCR_BLOCK_RAMP_CURVED_WALL  '}'  ///< curved ramp plus small wall
 #define LCR_BLOCK_RAMP_STEEP        '|'  ///< extremely steep ramp
@@ -712,18 +711,18 @@ void LCR_mapGetBlockShape(uint8_t blockType, uint8_t transform,
     {
       uint8_t 
         xRight = 6 >>
-          (blockType == LCR_BLOCK_LEFT ||
-          blockType == LCR_BLOCK_BOTTOM_LEFT ||
-          blockType == LCR_BLOCK_BOTTOM_LEFT_FRONT ||
-          blockType == LCR_BLOCK_LEFT_FRONT),
+          ((blockType == LCR_BLOCK_LEFT) |
+          (blockType == LCR_BLOCK_BOTTOM_LEFT) |
+          (blockType == LCR_BLOCK_BOTTOM_LEFT_FRONT) |
+          (blockType == LCR_BLOCK_LEFT_FRONT)),
         yTop = 4 >>
-          (blockType == LCR_BLOCK_BOTTOM ||
-          blockType == LCR_BLOCK_BOTTOM_ACCEL ||
-          blockType == LCR_BLOCK_BOTTOM_LEFT ||
-          blockType == LCR_BLOCK_BOTTOM_LEFT_FRONT),
+          ((blockType == LCR_BLOCK_BOTTOM) |
+          (blockType == LCR_BLOCK_BOTTOM_ACCEL) |
+          (blockType == LCR_BLOCK_BOTTOM_LEFT) |
+          (blockType == LCR_BLOCK_BOTTOM_LEFT_FRONT)),
         zBack = 6 >>
-          (blockType == LCR_BLOCK_BOTTOM_LEFT_FRONT ||
-           blockType == LCR_BLOCK_LEFT_FRONT);
+          ((blockType == LCR_BLOCK_BOTTOM_LEFT_FRONT) |
+           (blockType == LCR_BLOCK_LEFT_FRONT));
 
       ADD(0,0,0)      ADD(xRight,0,0)        ADD(xRight,yTop,0)     // front
       ADD(0,0,0)      ADD(xRight,yTop,0)     ADD(0,yTop,0)
@@ -737,7 +736,6 @@ void LCR_mapGetBlockShape(uint8_t blockType, uint8_t transform,
       ADD(0,yTop,0)   ADD(xRight,yTop,zBack) ADD(0,yTop,zBack)
       ADD(0,0,0)      ADD(xRight,0,zBack)    ADD(xRight,0,0)        // bottom
       ADD(0,0,0)      ADD(0,0,zBack)         ADD(xRight,0,zBack)
-
       break;
     }
 
@@ -843,14 +841,14 @@ void LCR_mapGetBlockShape(uint8_t blockType, uint8_t transform,
     {
       uint8_t right = blockType == LCR_BLOCK_CORNER ? 6 : 3;
 
-      ADD(0,0,0)     ADD(right,0,6) ADD(right,4,6)   // front/right
+      ADD(0,0,0)     ADD(right,0,6) ADD(right,4,6) // front/right
       ADD(0,0,0)     ADD(right,4,6) ADD(0,4,0)
-      ADD(0,0,0)     ADD(0,4,6)     ADD(0,0,6)       // left
+      ADD(0,0,0)     ADD(0,4,6)     ADD(0,0,6)     // left
       ADD(0,0,0)     ADD(0,4,0)     ADD(0,4,6)
-      ADD(right,0,6) ADD(0,0,6)     ADD(0,4,6)       // back
+      ADD(right,0,6) ADD(0,0,6)     ADD(0,4,6)     // back
       ADD(0,4,6)     ADD(right,4,6) ADD(right,0,6)
-      ADD(0,4,0)     ADD(right,4,6) ADD(0,4,6)       // top
-      ADD(0,0,6)     ADD(right,0,6) ADD(0,0,0)       // bottom
+      ADD(0,4,0)     ADD(right,4,6) ADD(0,4,6)     // top
+      ADD(0,0,6)     ADD(right,0,6) ADD(0,0,0)     // bottom
 
       break;
     }
@@ -862,58 +860,58 @@ void LCR_mapGetBlockShape(uint8_t blockType, uint8_t transform,
         mx = blockType == LCR_BLOCK_CORNER_CONVEX ? 4 : 2,
         mz = blockType == LCR_BLOCK_CORNER_CONVEX ? 2 : 4;
 
-      ADD(0,0,0)     ADD(0,4,6)     ADD(0,0,6)       // left
-      ADD(0,0,0)     ADD(0,4,0)     ADD(0,4,6)       // left
-      ADD(6,0,6)     ADD(0,0,6)     ADD(0,4,6)       // back
-      ADD(0,4,6)     ADD(6,4,6)     ADD(6,0,6)       // back
-      ADD(0,0,0)     ADD(mx,4,mz)   ADD(0,4,0)       // right
+      ADD(0,0,0)     ADD(0,4,6)     ADD(0,0,6)     // left
+      ADD(0,0,0)     ADD(0,4,0)     ADD(0,4,6)     // left
+      ADD(6,0,6)     ADD(0,0,6)     ADD(0,4,6)     // back
+      ADD(0,4,6)     ADD(6,4,6)     ADD(6,0,6)     // back
+      ADD(0,0,0)     ADD(mx,4,mz)   ADD(0,4,0)     // right
       ADD(mx,0,mz)   ADD(mx,4,mz)   ADD(0,0,0)
       ADD(6,4,6)     ADD(mx,4,mz)   ADD(6,0,6)
       ADD(6,0,6)     ADD(mx,4,mz)   ADD(mx,0,mz)
-      ADD(0,4,0)     ADD(mx,4,mz)   ADD(0,4,6)       // top
+      ADD(0,4,0)     ADD(mx,4,mz)   ADD(0,4,6)     // top
       ADD(0,4,6)     ADD(mx,4,mz)   ADD(6,4,6)
-      ADD(0,0,0)     ADD(0,0,6)     ADD(mx,0,mz)     // bottom
+      ADD(0,0,0)     ADD(0,0,6)     ADD(mx,0,mz)   // bottom
       ADD(0,0,6)     ADD(6,0,6)     ADD(mx,0,mz)
       break;
     }
 
     case LCR_BLOCK_BUMP:
-      ADD(3,0,0)     ADD(6,0,3)     ADD(3,1,3)       // top
+      ADD(3,0,0)     ADD(6,0,3)     ADD(3,1,3)     // top
       ADD(6,0,3)     ADD(3,0,6)     ADD(3,1,3)
       ADD(3,0,6)     ADD(0,0,3)     ADD(3,1,3)
       ADD(0,0,3)     ADD(3,0,0)     ADD(3,1,3)
-      ADD(3,0,0)     ADD(3,0,6)     ADD(6,0,3)       // bottom
-      ADD(3,0,6)     ADD(3,0,0)     ADD(0,0,3)       // bottom
+      ADD(3,0,0)     ADD(3,0,6)     ADD(6,0,3)     // bottom
+      ADD(3,0,6)     ADD(3,0,0)     ADD(0,0,3)     // bottom
       break;
 
     case LCR_BLOCK_RAMP_CORNER:
-      ADD(6,0,6)     ADD(0,0,0)     ADD(6,4,0)  // diagonal
-      ADD(6,0,6)     ADD(6,4,0)     ADD(6,0,0)  // right
-      ADD(0,0,0)     ADD(6,0,0)     ADD(6,4,0)  // front
-      ADD(0,0,0)     ADD(6,0,6)     ADD(6,0,0)  // bottom
+      ADD(6,0,6)     ADD(0,0,0)     ADD(6,4,0)     // diagonal
+      ADD(6,0,6)     ADD(6,4,0)     ADD(6,0,0)     // right
+      ADD(0,0,0)     ADD(6,0,0)     ADD(6,4,0)     // front
+      ADD(0,0,0)     ADD(6,0,6)     ADD(6,0,0)     // bottom
       break;
 
     case LCR_BLOCK_HILL:
-      ADD(0,0,0)     ADD(6,0,0)     ADD(0,2,1)       // front
+      ADD(0,0,0)     ADD(6,0,0)     ADD(0,2,1)     // front
       ADD(6,0,0)     ADD(6,2,1)     ADD(0,2,1)
-      ADD(0,2,1)     ADD(6,2,1)     ADD(0,3,2)       // front 2
+      ADD(0,2,1)     ADD(6,2,1)     ADD(0,3,2)     // front 2
       ADD(6,2,1)     ADD(6,3,2)     ADD(0,3,2)
-      ADD(0,3,2)     ADD(6,3,2)     ADD(0,4,4)       // front 3
+      ADD(0,3,2)     ADD(6,3,2)     ADD(0,4,4)     // front 3
       ADD(6,3,2)     ADD(6,4,4)     ADD(0,4,4)
-      ADD(0,4,4)     ADD(6,4,4)     ADD(0,4,6)       // top
+      ADD(0,4,4)     ADD(6,4,4)     ADD(0,4,6)     // top
       ADD(6,4,4)     ADD(6,4,6)     ADD(0,4,6)
-      ADD(0,0,0)     ADD(0,0,6)     ADD(6,0,0)       // bottom
+      ADD(0,0,0)     ADD(0,0,6)     ADD(6,0,0)     // bottom
       ADD(6,0,0)     ADD(0,0,6)     ADD(6,0,6)
-      ADD(0,0,6)     ADD(0,4,6)     ADD(6,4,6)       // back
+      ADD(0,0,6)     ADD(0,4,6)     ADD(6,4,6)     // back
       ADD(0,0,6)     ADD(6,4,6)     ADD(6,0,6)
-      ADD(0,0,0)     ADD(0,2,1)     ADD(0,0,6)       // left
+      ADD(0,0,0)     ADD(0,2,1)     ADD(0,0,6)     // left
       ADD(0,2,1)     ADD(0,3,2)     ADD(0,0,6)
       ADD(0,3,2)     ADD(0,4,4)     ADD(0,0,6)
       ADD(0,4,4)     ADD(0,4,6)     ADD(0,0,6)
-      ADD(6,0,0)     ADD(6,0,6)     ADD(6,2,1)       // right
-      ADD(6,2,1)     ADD(6,0,6)     ADD(6,3,2)     
-      ADD(6,3,2)     ADD(6,0,6)     ADD(6,4,4)     
-      ADD(6,4,4)     ADD(6,0,6)     ADD(6,4,6)     
+      ADD(6,0,0)     ADD(6,0,6)     ADD(6,2,1)     // right
+      ADD(6,2,1)     ADD(6,0,6)     ADD(6,3,2)
+      ADD(6,3,2)     ADD(6,0,6)     ADD(6,4,4)
+      ADD(6,4,4)     ADD(6,0,6)     ADD(6,4,6)
 
       break;
 
@@ -927,7 +925,6 @@ void LCR_mapGetBlockShape(uint8_t blockType, uint8_t transform,
       uint8_t x, y, z;
 
       _LCR_decodeMapBlockCoords(bytes[i],&x,&y,&z);
-
       LCR_TRANSFORM_COORDS(transform,x,y,z,6,4)
 
       bytes[i] = _LCR_encodeMapBlockCoords(x,y,z);
diff --git a/racing.h b/racing.h
index cca34f5..1cb8949 100644
--- a/racing.h
+++ b/racing.h
@@ -1,7 +1,8 @@
 #ifndef _LCR_RACING_H
 #define _LCR_RACING_H
 
-/*
+/** @file racing.h
+
   Licar: racing module
   
   This implements the racing physics and logic as well as replays and other
@@ -40,6 +41,7 @@ typedef int32_t LCR_GameUnit;  ///< abstract game unit
 #define LCR_RACING_EVENT_FINISHED    0x0002
 #define LCR_RACING_EVENT_CRASH_SMALL 0x0004
 #define LCR_RACING_EVENT_CRASH_BIG   0x0008
+#define LCR_RACING_EVENT_ACCELERATOR 0x0010
 
 #define LCR_PHYSICS_UNIT             4096 ///< len. of square for phys. engine
   
@@ -1211,7 +1213,10 @@ uint32_t LCR_racingStep(unsigned int input)
     _LCR_applyMaterialFactor(LCR_CAR_FORWARD_FRICTION,groundMat);
 
   if (onAccel)
+  {
     input |= LCR_RACING_INPUT_FORW; // accelerator enforces this
+    result |= LCR_RACING_EVENT_ACCELERATOR;
+  }
 
   if(!(input & (LCR_RACING_INPUT_FORW | LCR_RACING_INPUT_BACK)))
     LCR_racing.carBody.friction *= LCR_CAR_STAND_FRICTION_MULTIPLIER;
@@ -1330,13 +1335,13 @@ uint32_t LCR_racingStep(unsigned int input)
     if ((!LCR_racing.carDrifting) &&
       driftFriction > LCR_CAR_DRIFT_THRESHOLD_1)
     {
-      LCR_LOG1("drift start");
+      LCR_LOG2("drift start");
       LCR_racing.carDrifting = 1;
     }
     else if (LCR_racing.carDrifting &&
       driftFriction < LCR_CAR_DRIFT_THRESHOLD_0)
     {
-      LCR_LOG1("drift end");
+      LCR_LOG2("drift end");
       LCR_racing.carDrifting = 0;
     }
 
diff --git a/renderer.h b/renderer.h
index 3074f6f..c373090 100644
--- a/renderer.h
+++ b/renderer.h
@@ -1,7 +1,8 @@
 #ifndef _LCR_RENDERER_H
 #define _LCR_RENDERER_H
 
-/*
+/** @file renderer.h
+
   Licar: renderer module
 
   This implements 3D and 2D rendering. It should be possible to replace this
diff --git a/settings.h b/settings.h
index 1cba4f4..f64aa53 100644
--- a/settings.h
+++ b/settings.h
@@ -1,7 +1,8 @@
 #ifndef _LCR_SETTINGS_H
 #define _LCR_SETTINGS_H
 
-/*
+/** @file settings.h
+
   Licar: settings
 
   Compile times settings file for all modules, values here may be changed by the
@@ -159,7 +160,7 @@
 
 #ifndef LCR_SETTING_DEBUG_PHYSICS_DRAW
   /** If on, physics world will be drawn. */
-  #define LCR_SETTING_DEBUG_PHYSICS_DRAW 1
+  #define LCR_SETTING_DEBUG_PHYSICS_DRAW 0
 #endif
 
 #ifndef LCR_SETTING_POTATO_GRAPHICS