In the smart platformer ORUL, the shadows are not just a mass of shadows that follow you, but are mirror images that copy all of your actions and exist in a different realm, not necessarily the same geography as the real world.

In this minimalist platformer, the screen is divided in half. The upper half is the world of light and the lower half is the world of darkness (but not so black and white, since the color palette can be changed). When you move a small pixel character, its shadow follows, moving in the same horizontal direction, but in a reversed fashion, jumping up and down the screen.

However, there is one element of this scheme that does not quite match reality. Each figure reacts to terrain that does not exist on its own side of the screen and spins awkwardly in the air.

This misalignment, first with this asynchronous geometry, then with moving platforms, platforms that switch on and off, etc., quickly digs into the puzzle's goodness. It's a cooperative puzzle game where the other player is a clone of himself, monitoring two versions of the world simultaneously, each connecting to the other in clever ways. There are many other interesting little browser games on the developer's site, which I'll try out later. (Thanks, Warp Door.)

For more great free experiences, check out our roundup of the best free PC games.