There are 3 types of living enemies, all of which you can stomp or throw snowballs at.
The first and simplest is the penguin: he will only hurt you if you touch him from the front. From the back you can push him. It takes one snowball hit to kill him.
The second enemy is the polar bear: if you touch him from the front or back he will hurt you. He will notice you when you come too close and he will run to get you, if he notice you, he will roar and raise his paws to hurt you. If he is aware of you, you cannot stomp him, then you can only kill him with 2 snowball hits. If you approach him from the back, he wont notice you (unless you come too close) and then you can stomp him.
The third enemy is the most intelligent one: it is the Eskimo, he can shoot snowballs at you and jump at you when you try to jump him over, so be ware. It takes two snowballs to kill him, the first hit destroys his snowball gun. And the second kills him. Besides living enemies you have regular cannons and smart cannons, smart cannons shoot at you, while regular cannons just shoot in one direction. Also you have lasers that will burn you if you touch them, they will also burn your enemies so you can use that (push a penguin onto a laser). You also have sliding ice blocks, that move back and forth on a given platform, they are heavy so they will push you from the platform. You can stop them by standing on top of them. There are also spikes that you need to be aware of. To help you jump higher, there are red trampolines. You have 3 lives, the third time someone or something hurts you, you are dead. You can stand on ice or snow, ice is more slippery. You collect hearts when you are hurt. In order to pass a level you have to collect all the ice cubes in it. There are 9 levels, 3 are set in the afternoon, 3 at dusk, and 3 at night (the design of the background and the sun/moon movement changes).