Use the arrow keys to move. Use the space bar to attack with your knife, but it must be touching the zombie. If the zombies touch you for a full second without getting killed, you will die. You get points every time you kill a zombie, which will help you buy new weapons in the store. Paper is what you use to make the weapons. The white number in the store is how many points the weapon costs. When you buy the weapon, you will lose however many points it costs. The better weapons give you more paper and more points.
By the way, it is NOT finished. More is coming! (Only the sword is available in the store)