Kalypso Media have released their highly successful tactical simulation game Omerta: City of Gangsters on the MAC OS.
This version of Omerta actually supports the cross-platform functionality between PC and MAC, whilst also being supported by Steam Cloud saves.

The game is set on location of Atlantic City, Atlantic County, where players play as an immigrant that was born and raised in a tiny village in Sicily. The aim of the game, is to work your way up the ranks within the dangerous Mafia world and become the top don.
It’s set in the 1920’s era, where prohibition in the United States of America was extremely common. Once you get control of all the Mafia organizations, you’ll be the chief crime boss in the city.
Omerta: City of Gangsters is available now on the Mac for £29.99/$45, and you can acquire the title via the iTunes Mac Store, or through Steam.