Downloads (both have windows exe + source code and Linux makefile):
Uses SDL, SDL_mixer and SDL_image. I used kate for code/text, gimp for graphics, sfxr for sound effects (thanks DrPetter!), and pxtone to make music.
If the Linux version crashes when you run it on 32-bit x86, use this SDL library (contains a fix for a bug in SDL_SoftStretch)
Edit: Figured out the Windows sound latency issue! Seems the SDL.dll I used was buggy. Replacing it with one from libsdl.org fixes things.