Data Realms' Cortex Command is now out on the Mac. If you've already purchased the game then the same key can be used to play all versions. Mod support is included in this version (build 23), while the Windows version will be getting the updated build not long afterwards.

Apple Mac users can also expect to play a lot of Game Maker games very soon.

Cortex Command for Mac OSX is here
Game Maker 4 Apple Mac Update