Minecraft is a sandbox-building independent video game written in Java originally by Swedish creator Markus "Notch" Persson and now by his company, Mojang.
The game Minecraft is currently available in full since November 18, 2011 at a price of € 19.95 on the official website but it is still in development with regular updates.
A player in Minecraft has a lot of freedom to choose how to play the game, with the primary goals being surviving attacks by monsters (known in-game as "hostile mobs") and building shelter. The core gameplay revolves around construction. The game world is essentially made of cubes arranged in a fixed grid pattern which represent different materials, such as dirt, stone, various ores, water, and tree trunks.
While the players can move freely across the world, objects and items can only be placed at fixed locations relative to the grid. The player can gather these material blocks and place them elsewhere, thus potentially creating various constructions.
The game world is procedurally generated as the player explores it. Although limits exist on vertical movement both up and down, Minecraft allows for an infinitely large game world to be generated on the horizontal plane You can play alone in a dynamically generated map, or multiplayer on an existing server or created for the purpose.
Source : http://en.wikipedia.org/wiki/Minecraft and http://fr.wikipedia.org/wiki/Minecraft