Not sure how many of you know about this game, but I've been playing it for a while and just recently started playing it a lot more recently.
It's essentially a massive sandbox game, where you are plopped into a massive (essentially infinite) world, with nothing. And from there you can do what you want. You can explore, kill things, start digging, build a shelter, or start mining, or a combination of any of those. But what's awesome is the sheer breadth of what you can create. The game's Wiki has the crafting recipes for what you can make, and the way you can utilize these is awesome. It's surprising fun and addictive. Which is really surprising, since the game is still in Alpha.
But here's the best part. It's free this weekend to get hold of the latest version of game (not the limited trial on the website). See, Notch (the developer) tries to release new features or updates to the game every Friday. Well, it got released a day late today, and the sheer number of people updating the game caused the Minecraft servers to slow to a crawl. So Notch put the server in essentially a safe mode, keeping all basic things functioning, like saved games and user profiles. However, he disabled the ability to register and purchase the game, instead opting to make it free to play this weekend. Once he gets things fixed (He estimates by Monday) the game will go back to pay, so you'll have to buy it to keep playing (it's 10 Euros, so like $12-13). But it;s a nice time to see if you actually like the game and would interested in buying it. And Notch has noted that once you've purchased the game, you will never have to pay for another update or anything ever again. So it's a pretty sweet deal.
If you're interest, just go to Minecraft.net and scroll down to your operating system.
If enough of you guys like it and grab it, we can dick around in the multiplayer (despite it being buggy). It's actually quite fun. :x
