The issue here is that Counter Strike Global Offensive did have official Mac support. Then when CS2 came out, Valve replaced the CSGO client with CS2, rather than making it a new client, and then announced they're cutting Mac support. There is still a weird way to launch GO, but good luck finding players to play against now. It was pretty shitty of them to not leave GO as its own client or to not continue supporting Mac. This isn't quite a case of a new game not having Mac support, what happened from Mac users' point of view is their counter strike game updated and now they can't play it anymore.