Even if you own the game legally on Steam, the PC version has faced severe security vulnerabilities, including Remote Code Execution (RCE) Steam Community Public Lobby Danger:

: Features 8 remastered classic maps from previous titles in high definition.

Call of Duty: Black Ops III is a first-person shooter video game developed by Treyarch and published by Activision. It was released in 2015 for PlayStation 3, PlayStation 4, Xbox 360, Xbox One, and Microsoft Windows. The game is the twelfth main installment in the Call of Duty series and the sequel to Call of Duty: Black Ops II.

I don't recommend these due to malware risk, but for educational purposes:

A standard installation of Call of Duty: Black Ops III contains: