As usual, the concept of the game is really simple: you control a bird that throws snowballs, and you're off to fight a fire demon. So it's a shoot'em'up, but with an added twist: when you kill an enemy it doesn't just blow up and disappear, instead it starts falling down, moving with the same horizontal speed as it did before. Also, because it's now frozen, anything it touches that it's hot (which can mean enemies or switches) dies as well. This is a life saver for (for example) narrow vertical corridors filled with enemies. Also in the later levels you get to control some machines that have rockets - just block one of the rockets with snow so only the one you want works and then the machine starts moving.
The game lasts for about an hour or less so you can finish it in your first sitting easily. And here's the link if you want to try it out (which as usual I recommend!).