Super Derpy: Muffin Attack
A downloadable game for Windows and Linux
Become Derpy Hooves and fight with muffinzombies in this free software game in order to rescue Ponyville ponies so they can defeat Discord once again!
Equestria is again under Discord's attack! Now he's using an army of muffinzombies to bring back the chaos and lack of harmony into the land of ponies. But he didn't think about some mare who knows everything about muffins...
The game was never finished (there's just the beginning of level 1), but its engine lives on in many other games.