Not a big gamer, myself, but it seems like Valve has done a lot of work to make many (most?) Steam games run well under Linux.
Drivers have come a long way, and a lot of things just work, but it can definitely depend on what hardware is in your system.
I believe it’s tied to the ides of the restless dead.
The spirit should move on after death, but some spirits get stuck between worlds. Often it’s related to the circumstances of their death. Maybe they had unfinished business, they died a particularly grousom death, or they were denied a proper burrial.