You've got a good start to a game here, and with some more refinement you could make it into something pretty fun and different. I can't imagine it's very easy to make a game with just C and OpenGL, especially inside of a game jam timeframe, but I think you actually did okay. I think if there's one thing you could add to the game it'd be a jump button. It really felt like the game wanted me to jump over the bullets.

3D in game jams is always a nice surprise, even it's missing many levels of polish. I think reducing the amount of bullets would be good, because it's virtually impossible to dodge most of the time. Also, I wasn't sure what to do to win.