Ludum Dare is a game programming competition/jam that's been around for several years now. Currently it is divided into the Compo (also known as "classic" or "hard mode") and the newer Jam.
For the Compo entries are required to be made by a single person during 48 hours. Prior code is allowed but no existing assets may be used, and the full source must be available.
For the Jam the rules are more relaxed. Entries may be completed by a team and an extra 24 hours are available. Additionally, pre-existing assets may be used and the source code is not required to be available.
See Ludum Dare rules for details.
Entry for Ludum Dare 40 Compo (theme "The more you have, the worse it is")
Entry for Ludum Dare 39 Compo (theme "Running out of power")
Tiny Tily Tile World
My entry for the Ludum Dare 38 Compo ("A Small World").
My entry for the Ludum Dare Compo 37 (theme "One Room")
Die Die Die
My entry to the Ludum Dare 36 Compo (theme "Ancient Technology").
My entry to the Ludum Dare 35 Compo (theme "Shapeshift").