Comment by eevee

Overall, I don't think Doom 2 is actually much more abstract than Doom 1. I suspect the real difference is that all of Romero's levels were clumped together in the shareware episode of Doom 1, which is what everyone remembers. Sandy Petersen (who does the really abstract weird stuff) did episodes 2 and 3, but his Doom 2 levels were strewn throughout the game, even in the Earth-like sections that you'd expect to be more realistic.