I started this project about 2 years ago and then gave up on it about 6 months later because of lack of time, etc. Anyway, you can look at the source and learn if you like. The compiled version I have there only has one enemy, but the code is there for two different types of robots. I took the other type out because it was going slow on my crappy video card back then.
I edited out the nuclear glory key in the source, but the compiled exe is compiled with the unlocked version. I also didn't include the intro video because it's about 30 mb. Enjoy

You're welcome to finish it out if you like.