Zeno Clash is an excellent action game available only through online stores like Steam or Direct2Drive. It was developed by an indie developer, ACE Team, and has a visual style unlike any game I've played recently.

The visual style is reminiscent of a Tim Burton film or Jim Henson's Fraggle Rock or Dark Crystal. Weird creatures, odd weapons, surreal landscapes - Ghat's clothing is a mix of leather, wood, and odd animal shells and bones. The game oozes with character and personality.
The game does have some weaknesses. Towards the end, you'll be fighting 5 or 6 people simultaneously - and battles might consist of frantic circle-strafing, running, and punching. Some of the boss battles hinge on shooting which the game doesn't handle mechanically as well as the melee combat. The game crashed several times on my Windows XP machine. If you buy Zeno Clash, remember it's primarily a first person fighting game with some light shooting / rail shooting and light puzzle solving. It's not an RPG or an open-world game.
My opinion: this is a game everyone who likes action or FPS should experience. It's original and entertaining. Buying it will support an indie developer and Valve's Steam distribution method. If you don't want to spend $20 now, put it on your list and pick it up when a sale occurs. Definitely play it.