Shift 4Oh god. If you haven’t played Shifts 1, 2 and 3, go back and play Shifts 1, 2 and 3. Go on. We’ll wait.

All done? Fun, wasn’t it? And now you’re perfectly prepared for Shift 4, which expects you to be fully briefed on its brain-sizzling concept: press Shift, and the room flips 180 degrees, turning the walls into gaps and the gaps into walls. Like its predecessors, the fourquel improves as your mind and eyes start to work almost on automatic (it feels a bit like mastering the face and the vase). But this time, you’re using Ctrl to switch between multiple people — which ups the satisfaction that comes with trotting impossibly over/through/under/over walls to the exit. And offsets the motion sickness and possible vomiting.

Don’t miss the hidden unlockable achievements, either. Some of them can be earned before you’ve even started the game, hint hint. Play Shift 4 (Flash)