I'm not following the train of thought. How is having in-game battles recorded in history books an argument against being inside a game world? If anything, shouldn't that be evidence that they are in Valhalla's game world? Those battles don't exist anywhere outside of Valhalla, so the only place they'd be recorded in is within Valhalla itself.
Is the underlying argument I'm missing "the devs are too lazy, they'd never bother with adding player actions into the lore, therefore not a game world"? If so,