Comparter Needs a bit more
The gameplay has a value of about 60 seconds right now. Minimal work is necessary to increase the value to the 30-minute range, or even hours. So it's easy to salvage this one.
Here is my suggestion for improving the gameplay. Take it or leave it, but you get the idea.
Take the number of slots on the board, divide it by four, and you have a reasonable number of tile types. In this case, since you have 25 slots, the number of tile types should be 6, not 4.
I'd suggest increasing the number of slots, too, maybe 8-by-5 instead of 5-by-5, requiring 10 tile types.
Introduce more and more tile types as the game goes on, making the game harder and harder. Also, maybe add a minimum time between moves, so you can't just sit there and stare at the board.
Anyway, the art is good, the code seems to be running okay as far as I can tell, but you need to make it more challenging.
