Have you tried switching to X11 for these games? I have had similar problems on wayland. wayland is still beta-ish imo.

If you want to change the owner of fat partition, you can do it while mounting, e.g. mount -t fat -o uid=10,gid=10 ......

I always did make -j$(nproc --ignore=1) to avoid this while building cpp code. But this problem seems to be less severe if there are a lot of cores.