People who purchased Metal Gear Rising: Revengeance to play on their Macs will find some issues preventing normal play. Its DRM makes it impossible to play, due to the way it functions and closure of the company that created the port and its antipiracy measures. (Thanks, TryingtoWakeUpNow!)
Here is what happened. Transgaming handled the Mac port of Metal Gear Rising: Revengeance. It included DRM that required the game to check in with the company’s servers before people could play. However, Transgaming no longer exists and the final January 2017 patch for the version did not remove the DRM.
The Windows version of Metal Gear Rising: Reveangance is still functional. The Steam listing now also only notes that a Windows version is available.
Metal Gear Rising: Reveangeance is available for the PlayStation 3, Xbox 360 and Windows PCs.