Well, I now have SDL_mixer working in the game engine. I converted Trapper Zoid's level 1 song to a mp3 file, loaded it into the game, and it played just fine.

Well, not exactly. The song plays fine, but playing music causes the game to shudder. It basically leads to instances where the game will lag for double the normal time on one frame. So yeah, it needs to be fixed.

I'm going to test sound effects to see if they work as intended. Hopefully they will, because then I'll only have to fix half of the audio code.