Thanks for the clarification.

Does the Mac version run as well as it did on the PC version?

I run a Macbook Pro unibody (1st gen) and a Macbook unibody (1st gen) for reference, running Snow Leopard

I had purchased Darwinia years ago, still have a retail copy of it. Would it be possible to use my CDkey from the PC version on the Mac version, or do I need to buy a separate copy?

I loved this game, and would love to experience it again but on the Mac.