Puzzle-based action/platformer Trine 2 is coming out this week, and developer Frozenbyte has announced that the Mac version will drop alongside the Windows version on Steam. If you want to get a copy outside of the Steam system, you'll have to wait until sometime next year, but even with the "DRM," Steam is usually a good choice to go with, even on a Mac.
Frozenbyte is of course no stranger to Mac gaming, having just recently released a solid bundle for the Mac (as well as other platforms like Windows and Linux -- which is actually getting Trine 2 later on anyway). Trine 2 is looking like a really terrific game, expanding on the first title in the series by adding in new puzzles and puzzle types, making the lush graphics look even better, and including full online or local co-op gameplay.
Trine 2 will be unlocked on December 7 -- it's $15 for the standard game, or $24.99 for a collector's edition that includes an art book and soundtrack.