I'm sort of surprised there's not a thread about Minecraft here yet. It's an indie game made by one guy, and you basically mine stuff, and then craft and build things out of the materials you've gathered. At night, zombies, skeletons, and
exploding green penis monsters come to attack you, so if you haven't craft a sword/bow and some armor, you'd better get inside and hide until sunrise.
The game does cost, but it's only €10 (about $13 US), though the only accepted payment method is currently Paypal.
The game is in alpha, and apparently the price will double once beta hits, but alpha owners will get full access to all updated even after the price hike.
EDIT: Thought I should mention, upon launching the game you are prompted to log in, so I'm pretty sure it
requires an active internet connection. I know that's an issue in some cases.
Anyway, so I first found out about this game about a week ago, and I hesitated to pay for it until about 3 days ago. I bought it Saturday afternoon, and have done nothing else since. Damn I've spent a lot of time with it in just those couple days. I spent the entire first afternoon and evening building a dungeon into the side of a mountain, with a vertical shaft with a ladder leading up to the summit, where I would build my castle. Then the next day I noticed a lot of mountains in the distance that had large overhangs, and I decided to start over on one of those since a castle hanging off one of those would look way better. Then today I decided none of those mountains were large enough for a castle of the size I was imagining, and I was building right in the cloud place, which meant clouds passing through towers and causing my vision to look greyed out. I didn't like the idea of starting over again and leaving unfinished projects lying around my world. So I started a new world and instead picked a large valley with a mountain towering above it, which has an overhang just large enough for one tower to go up there (like a wizard tower or something).
This time it will be a village as well as a castle. So far I have my blacksmith building and the beginnings of my inn. I really need to wall it in or something, because the torches aren't keeping the bad guys away at night, and I find myself cowering in the blacksmith until the sun comes up. I also have a really deep mine where I've been gathering stone, and plan to run a mine cart track system through there to make heading in for mining a bit easier.
I need to figure out Iron Ore. I haven't seen any, I don't think. I've gotten stone, I've gotten coal, and I've gotten very little of a very stone-like ore, but it has brown spots on it. I assumed this is bronze or something, but I haven't tried to smelt it yet. I need iron so I can start making my mine cart tracks, but if it's this rare it's gonna take a while.
EDIT: Here's a screenshot of my second home, the castle on the overhang I had just started:
All I got done was most of the main tower, and a bridge across to a nearby mountain, also with an overhang. There's a small wooden block floating above the tower. That's my marker for the maximum build height (the tower would have gone up to there). The tower is intentionally crooked, which didn't turn out nearly as good as I had hoped. Also, you can see from this picture that the whole world is made up of large blocks with primitive textures. The character is two of these blocks in height, and one block in width/depth.