Zero Sum is another math-based game that ends up being pretty fun. It's a standard Match-3 style game like Bejeweled. The difference is that instead of swapping two tiles, the first tile you click gets added to the second tile, and the empty space is replaced with the tile waiting at the front of a queue of tiles on the right side of the screen. The tiles only contain the ones place of a sum, so in this game 9+1 = 0, 5+6 = 1, etc. The "zero sum" mechanic comes in when you add up numbers to equal 10, because a 0 tile is a wild card that can match with any two other tiles.