i just found this game by accident in the independent game developer site thingy, and let me tell you its pretty cool, i just bought it and its great, its a contructive puzzle game, meaning u have to build a structure in order to reach the goal, it doesnt have some fancy graphics but the game play is solid and pretty addictive, i cant get my sister off of it, heres the link... download the demo or support the game dev
http://www.worldofgoo.com/