In the news today, Microsoft bought Mojang for $2.5 billion. Mojang is famous for one product: Minecraft. Minecraft is like Second Life in that there are no specific goals for players to accomplish, allowing players a large amount of freedom in choosing how to play the game.
Although Minecraft is hugely popular, it has never appealed to me. The graphics are primitive and everything appears block-shaped, even spherical objects, like the sun and the moon. Here's a screen-shot of a scene from Minecraft, showing a couple of sheep: