VVVVVV developer Terry Cavanagh released a one-stage, first-person platformer presented in all red and gray. He started building Red Sky, which he says is a title about "interior decorating", for a two-hour game development event, but took some time to polish it and expand the single 3D level afterward.

It's fun but short -- you can complete it in just a few minutes -- and you're provided with no direction. You'll need to wander around with WASD/mouse controls, exploring every edge and looking at platforms from different angles/heights in order to find your way through. You can download it or play it through your browser for free here.