Ah, Minecraft. There's about a 40% chance you've heard of it. It's a little indie game by a developer, known primarily as "Notch" about a guy in an unfriendly world, trying to survive. It was only 15 bucks, so I thought I might help him out.
But... then I played it.
Damn. This game is, I can't stress this enough, HUGE.
Alright so I'll give you the rundown. You start a game in a randomly generated world, and you have one goal: survive. But no-one said it'd be easy. During the daytime, everything is nice. The cows are playing, the pigs are oinking, the sheep are... well... swimming at the moment. But then comes nightfall. The all-so-harmless world now shows it is infested by Zombies, Skeletons, Slimes, Spiders and explosive Creepers. If you aren't prepared, you're screwed. But I'll tell you about that later. Here's the basic enemies you'll run into during the fearsome night.
Zombies: Worthless. Slow, stupid, and weak. Consider them a great warrior if they can manage one hit.
Skeletons: Ouch! These creatures shoot arrows from distances and can be lethal if not approached with caution.
Spiders: At night, these eight-legged insects pounce on you. They can be defeated easily. They do not burn in sunlight, but are harmless during the day.
Creepers: Your number one fear. If they come within one square of you, say goodbye to your surroundings, current inventory items, life, and clean underwear.
Slimes: Never met one. Very rare. Presumably not very difficult to defeat.
And there you have a basic rundown of enemies. Due to space consstraints, I will end this here.
Watch for pt. 2 and survival guides.