If you've been known to kill time with browser games, Hundreds should immediately click with you. Created by Semi Secret Software, this dead-simple puzzle game for iPhone and iPad tasks players with increasing the size of various circles to accumulate a total of 100 points without letting them bump into other objects while growing in size.
From what I've played so far, that basic premise never really changes, but rest assured, there are plenty of clever mechanics which seek to complicate your path to 100. Some circles have negative point totals, and must be downsized before grown, while certain moving obstacles can be paused and unpaused, allowing you to get them in a prime location (i.e., out of the way.) It's almost terrifying to think about where this gradual progression is headed.
It seems like Hundreds would be best played on iPad, but it is a Universal App. Now through January 10, the game is available for $2.99. If you're in the mood for a great multi-touch puzzle title, consider giving this a shot.