Voxel Farm is a game framework for sale to developers who want to create cool, photorealistic environments. But the demo, called Procedural World, is a Minecraft clone that I would pay big bucks for if it were available for sale.
Minecraft, you'll recall, is a 3D sandbox game that uses a very specific and very wonky 8-bit style. You run around the world with your axe and hammer through rock and stone, building houses and avoiding baddies. Procedural World essentially mirrors this process – complete with the mining – in an environment that looks like Far Cry met a box of LEGO.
The video above shows some of the basic features and an older video, below, gives you a really in-depth look at the environment. The creator, Miguel Cepero, blogs about the game here and you can license the engine here. There's not much information on whether he's actually launching this thing but I'd suspect Notch wouldn't be overly upset if a beta version ended up in my mailbox somehow so I could play the heck out of it. Sadly, there are no zombies in Procedural World (yet) so there's no opportunity for some photorealistic gore.