World of Goo is a physics based puzzle game that is incredibly cute, funny and most importantly, seriously addictive.
This has been a big hit on PC and Mac for a couple of years now, but the wait for an iOS version has been worthwhile. The game is just as engaging as always, but has been optimized for touchscreens which has worked really well. The iPhone version works despite the smaller screen size and is just as much fun as the iPad game.
Every level challenged you to build structures out of Goo Balls, of which there are several species. By dragging the balls around, you can create bridges and towers that other Goo Balls can use to get to the escape point. Gravity means you have to watch the balance of your structure, and there are tons of really interesting and inventive levels that get you to build structures in different ways.
There are five chapters to the story part of the game, and also the World of Goo Corporation. This holds all the Goo Balls you have saved during the story, and you are simply challenged to build the highest structure you can.
World of Goo is one of the best games you'll play on iOS. The puzzles are great, it's challenging but fair, and the atmosphere and graphics are enough on their own to keep you coming back for more.