The developers of World of Goo had an interesting promotion: download the game and you set the price! Always the cheapskate, I bought the game for only $4.99 (couldn't make myself only pay $0.01, no matter what my shoulder devil encouraged me to do). This game more than paid for itself at $4.99, and could easily go for $14.99. Although I enjoyed the game, there were some serious wallbanger parts, where I was glad I'd spent the extra money a year ago on the heavy duty mouse. The game is based on a physics simulator, and this is both the game's charm... and the reverse "blessing" which will cause you to curse like a sailor.