I have played this game all the way through several times now. I love that I can play with no time limit, and it's really several different games because the rules change a bit in each area. For example, in the desert the goal is to collect the letters, but that's the only area that even has letters. Another area has two special pieces that spawn at the top, and you need to get them down to where they are on the same horizontal row with no obstructions between them - then they combine (the goal) and a new pair spawns. With some boards the best strategy is to avoid removing the locks on certain tiles (so that the freezing can't escape to annoy your play) and others the best strategy is to remove the locks and freezing tiles first, then concentrate on the actual goal. The swirl to try to fix "no moves left" boards can also be used strategically to fight the freezing when it starts getting out of hand.
I'd like to see a sequel to this game, particularly if it had "endless play" modes on the boards that spawn special pieces (just keep spawning them, and see how high you can get perhaps).