'Cut the Rope: Experiments' is free in all supported territories on the improved Amazon Appstore today only.
If you use the Amazon Appstore in the UK you'll have noticed that up to now you've only been able to browse the applications on your device. You'll be pleased to hear that you can now use the Amazon UK website too!
The Appstore itself (complete with the free app of the day) has now expanded to over 200 countries around the world, so if you were excluded before, there's a good chance you can get your freebies now! :)