Hello again, I seem to have a small problem with my game when it comes to including a definition more than once. I believe the best way to explain it is with the troublesome code... Game.h

#ifndef _GAME_H_
#define _GAME_H_

//Inlcudes
#include "Echelon.h"

//Game Function Declarations
void GameStart(EchelonEngine* engine);
void GameEnd(EchelonEngine* engine);
void GameStep(EchelonEngine* engine);
void GameRender(EchelonEngine* engine);

//Game objects
Camera cam;

#endif

and now the echelon engine header Echelon.h

//Echelon Game Engine
#include <windows.h>
#include <gl/gl.h>
#include "Camera.h"
#include "Game.h"

#ifndef _ECHELON_H_
#define _ECHELON_H_

//engine class definition OMITTED FOR SPACE
#endif 

The error visual studio gives me is... 1>Echelon.obj : error LNK2005: "class Camera cam" (?cam@@3VCamera@@A) already defined in Game.obj I'm guessing this is a result of Game being included more than once but I thought the #ifndef took care of that. Whats going on here? Thank you!

Thanks for the help! In light of your responses I shifted some things around and it now works. One thing I wanted to keep was the ability to keep the game files simple Game.h and Game.cpp so I fixed the problem by moving the game function declarations to there own separate header and let the engine include that and not the new Game.h which is only the declaration of the camera and anything else I need for the game. Thanks for the help.