Thanks for the great game - it was keeping us all busy here last night.
I have a few suggestions for enhancements:
1) Keep a count of the number of Hexa's cleared each pass and award bonus points for clearing 10, 15, 25 at a time. This would bring a different strategy to the game.
2) Add a high score table for total score and max cleared in one colour choose.
3) If the player clears each game with either 0 or 1 goes left then after 3 games like this start introducing 'clear'/non coloured hexa to make it harder (I'm evil