Minecraft is a game about placing blocks to build anything you can imagine. At night monsters come out, make sure to build a shelter before that happens. You must have Java to play this game.

WASD to move.
Space to jump.
R to respawn at the spawn point.
Enter to set a new spawn point.
B to open the inventory.
F to toggle fog distance.
Escape to release mouse and open game menu.
1-9 or scrollwheel to change building block type.
Left mouse button to add a block.
Right mouse button to remove a block.
Middle mouse button to copy block type.
In multiplayer:
Tab to list players.
T to chat.