Doom looked significantly worse than this, though. It was very low resolution and ran pretty slowly. There's SuperFX chip, but most SuperFX games used mostly untextured polygons with very limited textures. If this game would be possible on SNES, it would definitely run at much worse framerate and lower resolution.
Also I would say a bunch of games of e.g. Sega Saturn looked almost exactly like this game. I wouldn't say it looks *that* different from some early PSX dungeon crawlers, like e..g Crime Crackers.