My parents were not happy when i played Minecraft. But that turns all: The game is set in a virtual world made of cubes of different materials - dirt, rock, sand, lava, obsidian and many more. Almost all of these can be used as building blocks and a few can be refined into usable raw materials (wood, iron, diamond etc).
That means: Minecraft isn't just a game, it's a game in wich you learn something!