The graphics exclusively used real-time rendered polygons with support for transparency, which nobody knew was even possible at the time. Along with researching the new rendering tech, the same person created everything else except the music - the memorable & immersive world, an original story, concept and cover art, strong cinematics that were SoTA at time, graphics and animation, innovative level design, puzzles, the game logic - over just 2 years. It also defined a new 'cinematic platformer' genre, with later titles like Flashback, Blackthorne, Oddworld, and recent LUNARK. It's simply incredible feat.
Aegis Animator was doing pretty much the same sort of rendering on the Amiga, in 1985.
I never did much with it, what with being a kid at the time, but it was fun to play with and looked pretty cool. I don't think its rendering was as tightly optimized as Another World's was, though.