i am passion about 3D Game development , virtual reality and graphics and modeling, in the 3D Game development with help of game engine we can i improve our productivity and save our time , i hope its depend on genre of the game , now we have plenty of free engine available internet check the list List_of_game_engines . I implemented my 3D game by UDK game engine , watch the videos i uploaded for my game and i mention bellow about game design and document about my Game