Mr. duck and the room0 was my entry of the Ludum Dare 31. In this game, you're a duck who must collect the 25 pearls. For every pearl you collect, a new enemy will appear.
Very simple game mechanics, you have a certain amount of "stamina" for flying. And a new challenge appears every time you get a pearl, signifying the "level" you're on, meaning 25 pearls/levels in total. The design of the game is simplistically beautiful, and overall an enjoyable game.