That only goes so far though. A lot of games need internet access, so essentially you are running potentially modified binaries running on your hardware/network, that gets access to the outside. Sure, blast radius becomes somewhat limited, but you still have a potential problem.

The only games that need a network connection are online games. With those you can use a application firewall (which you should anyways) like opensnitch to only allow connections to sites that make sense and block anything else e.g. internal connection.

Unless you get your cracks from google.com it will be fine.

Flatpaks would make it easy, if they ever worked when you needed them to.

Sounds like a issue with your system. I have used hundreds of them on all kinds of systems.

I'm glad it works on your machine.