You won't be able to save unless you log in. This game requires Java. Press escape to release the mouse. Press B!

Controls:

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