Rollercoaster Tycoon 3 Update for Mac
The download only contains an incremental update to the actual product, which has to be acquired separately.
Publisher's Description
From Aspyr Media:
What this update does: Runs natively on Intel-based Macs. Fixed a crash when communicating with iTunes to retrieve the "RCT3" playlist. Cmd-Tab and Cmd-H can be used in fullscreen mode to switch in and out of the game.