You need to sneak through each level. Very, very carefully. And you will die. A lot. Fortunately each level is pretty short and has checkpoints. The main problem, though, is the levels are all linked...for example in one level you can turn on a tap. In another level, later on, it'll be flooded and an item you need to advance will be revealed. A lot of them are less obvious...I remember one was digging up something in a garden. You will need a guide to complete this game, I assure you.