You're supposed to fill up machines with ichor on each floor and return to the elevator to descend further when finished. Each floor has a number of Twisted Characters (starting at 2 and capping at 6) that are trying to kill you. Depending on which character you play as, you have either 3 or 2 hearts before dying. The reason I'm stressed is because the Twisted Toon in the back is the fastest Twisted in the game, and can spot you halfway across the floor map. In Panic Mode (where you have to run back to the elevator before it leaves once you finish the machines on the floor) Twisteds get faster. So um...
Stressful!