Major retexture with unique, new set?

[Danfun64]

Why not have Phase 2 solely be aimed at Doom 2 compatibility, and have separate Final Doom compatibility PWADS for whenever someone plans to play a Final Doom level?

[Nikita_Sadkov]

MrFlibble said:

Raven Software had their own previous games with graphics and other art to use as placeholders (and some actually served as the basis for the assets in Heretic and Hexen), but I think it would not be improbable to suppose that, if these two games were developed by id Software instead, maybe they'd use Doom graphics as placeholders or bases for new assets as well.

Their monsters do appear to be similar in design, although little better with each iteration. Guess they were done by the same concept artist.