Deus Ex: Mankind Divided, BioShock Infinite, and the Metro franchise are my favorites, especially the Metro. I even bought the Redux bundle on Steam recently in order to play it again and check out the Exodus. But right after you finish them, it is always CS:GO
It's too bad Half-Life 2: Deathmatch doesn't work on Catalina because that was a killer game. Population has declined but a good bot mod and it's still a good game. You could probably play it on Windows in Bootcamp but that may be too much effort. All of the Valve shooter games are good. I used to be obsessed with Team Fortress Classic around the year 2000.