Crater Creator
Community Moderator
After mulling it over with moderators, no more discussion of playing without Steam, please. It's too close to discussing piracy, which is against the rules. Officially, you need to be running Steam to play the game, and this is intentional.
Now, as far as ways to play that still use Steam... the OP is on a Mac, and Apple provides Boot Camp to run Windows & Mac partitions on the same system. If your company only cares about software installed on the Mac partition (I'm guessing they wouldn't give you a Mac unless your work was done in macOS), you could create a Windows partition with Boot Camp and play the game on that.
Advantage: you'd likely experience better performance under Windows anyway.
Advantage: you have to reboot between operating systems, which creates a psychological barrier between work and play.
Disadvantage: there's no security layer per se between the two partitions, so if Steam led to some malware that indiscriminately corrupts data, it could reach your important work stuff on the Mac partition as well as the Windows partition. Your IT department will likely not be happy with you.
Now, as far as ways to play that still use Steam... the OP is on a Mac, and Apple provides Boot Camp to run Windows & Mac partitions on the same system. If your company only cares about software installed on the Mac partition (I'm guessing they wouldn't give you a Mac unless your work was done in macOS), you could create a Windows partition with Boot Camp and play the game on that.
Advantage: you'd likely experience better performance under Windows anyway.
Advantage: you have to reboot between operating systems, which creates a psychological barrier between work and play.

Disadvantage: there's no security layer per se between the two partitions, so if Steam led to some malware that indiscriminately corrupts data, it could reach your important work stuff on the Mac partition as well as the Windows partition. Your IT department will likely not be happy with you.