My rendition of my favorite TI-85 calculator game
Falldown is a game in which you guide a ball through gaps in a rising floor. If the ball gets squashed at the top of the screen, the game ends.
These seem like leading questions.. Uhm, Falldown Rebirth is mostly open-source. As of this writing, all of the game's source code is available via GitHub. However, there is some supporting source code (for e.g., vector math and collision detection) that I have not put up on GitHub yet.