iOS appstore (recommended)
This is a new puzzle game.
It's today's free game on the "Advent of Indies" calendar. I used this as a deadline to motivate me to finish it. I'm quite pleased with how it turned out.
(Oh, and if you enjoy this you'll probably like Game Title and Lost Levels, and vice versa.)
edit 31/12/2012: Minor bug-fix update.
edit 06/01/2013: seems to not be working for people on Windows 7. Trying to fix this now.