I have written about Cut the Rope before. In this cute puzzle game for iDevices you must cut the ropes in the right way so that the candy falls into the mouth of a cute little monster.
If you have not tried it before you should give it a try. Currently there is a new universal app available for free for the holiday season: Cut the Rope Holiday Gift.
Cut the Rope Holiday Gift is not a demo but rather a free bonus app. There are no overlaps of the levels with Cut the Rope.
When I wrote this post, I was looking at version 1.0 for iPhone, iPod Touch and iPad. It is a universal app and supports Game Center. Requires iOS 3.0 or later. Available in the AppStore.
Tried with iOS 4.2 on an iPhone 3GS.