You Need Closure

Flash game supremo, Tyler Glaiel, follows up Aether (co-created with Edmund McMillen) with a new, imaginative puzzler, Closure. The all-important unique device: if it isn't lit up, it doesn't exist.

It's an extremely smart idea. Orbs of light can be picked up and carried, or placed in moving devices, such that areas of the level are lit. If it can't be seen, it isn't there. So if there's a wall in front of you, get past it by casting it into the shadows. Darkness is a tool.

This very quickly becomes extremely difficult, offering tough challenges a third of the way through its 30 levels. New orb types appear later on, along with locked doors and keys, and various new tasks. But what makes the game more than a new gimmick is the intelligent application. You're asked to rethink how you platform with this new device in mind, and in no way handheld. In fact, you're going to have to embrace its ideas to start the thing at all. Well worth checking out.