I thought about this for 5 minutes and really got nowhere. Can anyone come up with a nice analytic way to think about an algorithm?

There are a couple of brute force approaches: a) always pick the direction that will result in the most blocks to combine, b) always pick the direction that will result in the largest score.

I know someone was working on an AI that plays Threes (the game that inspired this one). Haven't seen any code from him though.

http://forums.toucharcade.com/showthread.php?p=3142737#post3...

I think you want to keep the large numbers in the corner.

How about using A* algorithm?