You can buy "Trine" for the PC for £14.99 at Gameplay.co.uk, and that is with free delivery too. The next best price I can see for this online is £17.99, so it's a saving of a few pounds.
According to the gamespot reviews, this game gets a rating of 7.5/10, which isn't bad.
" In Trine', players work together to create and use objects to solve challenging physics-based puzzles and defeat dangerous enemies. Set in a kingdom on the verge of chaos, a warrior, a wizard, and a thief are bound by a powerful artifact known as "the Trine". Together, they must battle the forces of space, energy, and motion to put an end to the reign of the dark sorcerer that rules the kingdom."