There is no objective, this is a sandbox game!

White square is the player.
Top left shows your inventory, center is your health.
The off-white squares are sheep. Pink are pigs, brown-ish are cows. Aqua-green squares are zombies.

Use W, A, S, D to walk.
Up, down, left, right to change direction.
1 through + to choose an item in your inventory.
Space to interact/place an item.

Note: wool on top of wood makes a bed, interacting with a bed allows you to sleep.
Harvesting 3 wheat and placing the blocks next to eachother 3 in a row produces bread.
Things may seem to disappear, but it's probably because you're in a hole or water.