This could be interesting, but fix the response to moves. Annoying to try and move a stone only to have it ignore the touch and then get blocked by the next arriving stone. The game gets hard fast enough without having to feel like it cheats as well.
And once the board gets over half full, it becomes way too hard way to fsst and very un-fun quickly.
A little tweaking, some level and pacing controls, and better response to moves, and this could be good. For now, I will not play much more.
MajorHavoc about Flipstones, v2.0