I've not had any issues running the game without Galaxy, but it seems like the game starts going haywire after a few hours. I was able to fix this by using Galaxy's "verify and repair" function, but obviously that's not always the best idea if you don't wanna go through Galaxy. I suspect the issue might be one of caches, as the game just randomly stopped working. Any idea where the cache would be stored? I'm tempted to try to delete it manually next time it starts flat-lining, see if that hypothesis is correct.