The boxes line up with the grid that the tip of your mouse cursor is on. It's not intuitive, but once you realize this, it's easier to have precise control. (Focus on where your cursor is, rather than where the box is).
Really great for a 48-hour challenge.
Without too much instruction, it was easy to figure out. Difficulty was there, but barely frustrating. If you ever give yourself more time on this one (or a sequel), I'd like to see the final "color"/mode explored a bit more... all of the sudden it was an action game instead of a puzzle game and that was cool.
Also made a shoot-in-all-directions death machine: guns (10 energy, 0 homing, full everything else) pointing in all 24 directions. I can get up to a 1014 combo, but can't pass it. I wonder if it has to do with framerate (meaning, why can I regularly get up to 1014 but oddish can only get up to 1013).
Only $4.99 through Steam. Well worth it. This game is truly excellent. Also, for anybody interested in Super Meat Boy, the playable character in VVVVVV was just announced for the PC/Mac version of SMB.
It's a good concept, but it's execution is only okay. In games that require precision, the player needs more precise controls. The gravity is too light, the balls are too bouncy, and the spin control is too loose.
@TBTabby, multi-color is definitely part of the game. You can still solve all the multi-color ones with logic... it just doesn't go as fast because you can only place X's when two same-color numbers are adjacent.