I said it in these videos, but with regards to theme, Unreal's mixture of ancient temples, medieval castles, and tech bases has more in common with Quake than Quake II. It is, to be honest, really hard to reconcile all of that and Quake barely bothered, setting it all in a Lovecraftian nightmare realm with no lore aside from "bad guys are coming from different dimensions, we've code-named the leader 'Quake,' go stop him." The thing is though, all that weirdness worked *because* they didn't go out of their way to justify it. You can get away with a lot if you just explain the bare minimum; it's when you start wanting to hash out details that it starts to get bogged down, which is kind of what happened with all the translator data dumps and the inclusion of a detailed backstory in general.
