To complete each level, you must fill the ghoul harvest meter by destroyinh the undead any way you can.

Each time you get hit by a monster or a bullet, you lose some life.

Up Arrow: Look Up
Down Arrow: Look Down
Left Arrow: Move Left
Right Arrow: Move Right

X: Jump (Tap twice to double jump, or press jump+down to jump down)
Z: Shoot(+ Direction to aim up, down or diagonally)