Apparently MSVC is convinced that there's an important, linking-breaking difference between classes and structs. (Bug#1093, Thanks root670 for the patch!)

src/Course.h

@@ -14,7 +14,7 @@
 
 struct lua_State;
 class Style;
-class Game;
+struct Game;
 
 const int MAX_EDIT_COURSE_TITLE_LENGTH = 16;
 

src/FontManager.h

@@ -4,7 +4,7 @@
 #define FONTMANAGER_H
 
 class Font;
-class Game;
+struct Game;
 
 class FontManager
 {

src/GameCommand.h

@@ -16,7 +16,7 @@ class Course;
 class Trail;
 class Character;
 class Style;
-class Game;
+struct Game;
 struct lua_State;
 
 int GetNumCreditsPaid();

src/GameManager.h

@@ -4,7 +4,7 @@
 #define GAMEMANAGER_H
 
 class Style;
-class Game;
+struct Game;
 struct lua_State;
 
 #include "GameConstantsAndTypes.h"

src/GameState.h

@@ -19,7 +19,7 @@
 
 class Character;
 class Course;
-class Game;
+struct Game;
 struct lua_State;
 class LuaTable;
 class PlayerState;

src/InputMapper.h

@@ -4,7 +4,7 @@
 #include "RageInputDevice.h"
 #include "GameInput.h"
 #include "PlayerNumber.h"
-class Game;
+struct Game;
 
 const int NUM_GAME_TO_DEVICE_SLOTS	= 5;	// five device inputs may map to one game input
 const int NUM_SHOWN_GAME_TO_DEVICE_SLOTS = 3;

src/NoteSkinManager.h

@@ -7,7 +7,7 @@
 #include "GameInput.h"
 #include "IniFile.h"
 
-class Game;
+struct Game;
 struct NoteSkinData;
 
 /** @brief Loads note skins. */

src/Profile.h

@@ -59,7 +59,7 @@ class Style;
 class Song;
 class Steps;
 class Course;
-class Game;
+struct Game;
 /** 
  * @brief Player data that persists between sessions. 
  *

src/StepMania.h

@@ -1,7 +1,7 @@
 #ifndef STEP_MANIA_H
 #define STEP_MANIA_H
 
-class Game;
+struct Game;
 class RageTimer;
 class VideoModeParams;
 

src/Style.h

@@ -14,7 +14,7 @@ const int MAX_COLS_PER_PLAYER = MAX_NOTE_TRACKS;
 static const int Column_Invalid = -1;
 
 class NoteData;
-class Game;
+struct Game;
 struct lua_State;
 
 class Style