I can't link it out and the error message below:
Linking...
main.obj : error LNK2001: unresolved external symbol "public: __thiscall example_Engine::example_Engine(void)" (??0example_Engine@@QAE@XZ)
main.obj : error LNK2001: unresolved external symbol "public: __thiscall example_Engine::~example_Engine(void)" (??1example_Engine@@QAE@XZ)
main.obj : error LNK2001: unresolved external symbol "public: void __thiscall game_Engine::Render(void)" (?Render@game_Engine@@QAEXXZ)
main.obj : error LNK2001: unresolved external symbol "public: bool __thiscall game_Engine::Update(void)" (?Update@game_Engine@@QAE_NXZ)
main.obj : error LNK2001: unresolved external symbol "public: bool __thiscall example_Engine::Init(unsigned short const *,enum irr::video::EDriverType,int,int)" (?Init@example_Engine@@QAE_NPBGW4EDriverType@video@irr@@HH@Z)
Debug/main.exe : fatal error LNK1120: 5 unresolved externals
Error executing link.exe.
main.exe - 6 error(s), 0 warning(s)