Move uses LEFT & RIGHT arrows, with UP to jump. Open the Blood Magic screen using the E key, here you can exchange parts of your body for more magic.
BEWARE! Sacrificing body parts will hinder your abilities! Without legs, you cannot jump high or run fast. Without arms, you cannot balance yourself. Without eyes... well you cannot see!
In certain levels, you can use the F key to activate Light Bridges, these make the path easier but cost you Magic Points.