I am interested in making a game with an open source engine. The game will not be using any high def textures but will be going for a simple look. I plan to make it almost like a 3d tour of an area that you can interact with. The game will be single player. I know doom3's code base is open but it looks pretty massive. Is there a smaller tool for this job that also has a map editor, like is quake 2 a good candidate? I have knowledge of C, Java , and Python.
Thanks for reading,