I don’t think back4blood supports playing without eac, as it is multiplayer online game.
flatpak is a good idea, but there are 2 problems with it
1) by default, it writes tons of stuff to /var and all app data goes to /home - filling up system drive with games.
This can be worked around quite easily though, so it’s not a big deal
2) Correct me if I’m wrong, but flatpack steam comes with its own libraries, including mesa, effectively negating any performance benefits from v3 mesa build. And apart from steam and games, there is no much use for high performance mesa optimizations in the first place.
So I would rather use patched glibc, but it seems arch devs aren’t interested in patching glibc anymore.
And it would be rather unlikely to get windows games patched for linux (which has like 1% market share), unless valve does something to remedy this situation.
SteamOS is arch based, so it would be quite embarassing if it couldn’t run games.