I don't think that you've written 980 MB of code. Even from extremely laborious coders, I've never seen code of more than a few MB.

Unless you've programmed a new Windows in lite-C, the allocated 980 MB are probably used for your images, sounds, large data structures, and so on. Go through your game and check what you really need and what you can reduce. Use DXT images rather than BMP, and OGG sounds rather than WAV.