https://marco.org/2008/12/03/design-tour-world-of-goo-this-puzzle-game-is
This puzzle game is incredibly fun and smart, and the graphics and sound create an amazing atmosphere. Watch this design-tour video (created by a fan) to get a sense of how good it is, then download the demo.
If you like it, and I think it’s pretty likely that you will, support the two guys who made it by buying the full DRM-free version for Windows, Linux, or Mac OS X for $20. (It’s also available on WiiWare, whatever that is.)
I’m rarely this impressed by a game. It’s truly first-class. Even if you don’t usually like games that much, give this a try.
(edited to replace the Vimeo video with YouTube because Vimeo has so many users that they need to kick out many of the great ones)