It can be. It's a completely single player game, but there are servers that people host where people meet up and just start digging. Normally where you end up with some massive projects being undertaken.
Someone made a completely functional mathematical calculator. Strange heh.
It's basically just a massive sandbox for doing what you want. The graphics are very basic (although you can download texture packs that improve them).
Generally a server will be in survival mode. So people share resources and find themselves a nice little area to build themselves a home. Check out some youtube videos of what people have built. Mighty impressive some of it.
Of course, a public server opens up the potential for the odd griefer to turn up and redirect the carefully constructed lava trap you made into your front room
The single player survival game is basically a tense affair as you slowly mine further down, uncovering caverns as you go and laying torches everywhere! Generally one of those games that needs the wiki open so you can learn what crafts what. For example, get some wood, use your craft bit and you can make a craft table. Then with some stone can make a better pickaxe. Eventually a sword etc... They still develop it, so it's still having stuff added to it. Definitely try out the link I posted to the free version. I just enjoyed digging for a while and seeing where I went. Then I built a house
Edit/// To any mods, feel free to move all these minecraft posts into a minecraft thread of it's own
