It's simple. Shoot the enemies and get upgrades (weapon type, speed, and shoot speed). If you get hit once you're dead. High scores save onto your computer, so you can exit the browser if you like and the high score will remain.
ASDW are used to move the ship.
Your mouse is used to aim your blaster.
You cant turn off and on the sound by the buttons at the top right of the screen.
Circles- they flood you. they get faster too.
Squares- they are like zombies. they are slow, but have quick bursts of energy. Don't get too close.
OctoPies- these guys are slow, but when hit, break into pie pieces.
Snakes- snakes are quick and sly. Watch out. They can suprise you.