Frozenbyte now offers betas of the OS X and Linux editions of Trine 3: The Artifacts of Power, their action/platformer sequel. The betas are available on Steam along with a new patch that has a number of fixes and changes to the Windows version of the game. This announcement covers all the details of the Windows patch and the new betas, including a list of known issues, though there is no indication at this point when to expect the new releases to leave beta. If you want a refresher, here's an overview of the game:

Trine 3: The Artifacts of Power is a 3D platforming game of action, puzzles and adventure.

Experience a fairytale world of breathtaking sceneries and face a myriad of physics-based puzzles, wonderful contraptions, dangerous foes and enchanting creatures.

Playable in single-player or in co-up with up to three players, both locally or online.