Dragon's Lair.
This just graphically blew everything else out of the water at the time. Being able to (sort of) play a cartoon was so cool to me as a kid. Sure the gameplay sucks and this is the great granddaddy of the maligned quick time event, but the graphics were unparalleled, especially in the 80s. I think my amazement at this game as a kid has carried over into the graphics I tend to like now, which are often more cartoonish and stylized than they are realistic.
Ninja Gaiden (NES series).
This was my first experience with a cut scene in a game. They managed to make Ryu appear to be the most badass man alive and it was the first time I ever felt a videogame was cinematic.
Shin Megami Tensei: Nocturne
I love the art style of all the Shin Megami Tensei games, but there is just something so other worldly about Nocturne that makes it feel creepy and cool all at the same time.
Another World (aka Out of This World)
This game did so much with so little. Truly ahead of its time and a masterpiece of minimalism.
Borderlands
Borderlands was once going to be a realistic looking first person shooter. They made a bold move to change the artstyle to look more like a comic book and they took cell shading to a whole new level.
Phatasmagoria
Maybe it's cheating to put in an FMV game, though there are 3d rendered backgrounds. What I love about this game though is just how ordinary looking the characters are and just how much this game makes me feel like I'm in a b-movie horror film.
F-zero Sharp angles and bright colors, F-zero felt futuristic and vibrant.
Okami
A list like this wouldn't be complete without Okami. This is the one game that gives you the experience of walking in a japanese water color painting.
Zeno Clash
Everything felt weird and alien, brutal and fantastical. In a time when most games look like realistic war simulators, space marine simulators, or zombie apocalypse simulators full of heavy greys and browns, Zeno Clash takes you to some bold and bizarre looking fantasy world.
Q-bert
Q-bert is the MC Escher of the videogame world. They didn't have a lot to work with back then, so they gave you something visually confusing to look at and filled it with odd cursing characters.
Gridrunner Revolution
This is sort of like playing screen saver: the game, but I love the references to old school games and the trippy coma inducing/seizure inducing visuals. It's really brilliant in a strange way. It's definitely a unique experience, yet it carries the heart of the early 80s arcade shooter.
Persona 4
Everything in this game oozes with a cool style, even the menus. It's so consistently done that it gives the whole experience of this insanely long game one cohesive personality. It's also unabashedly Japanese, which is a rare treat for a game released in the US because most developers hide the cultural specifics from us to make them more relateable for Western audiences.
Shadow of the Colossus
The colossi are noble beasts. The sun washed world they live in is desolate and beautiful. The buildings are ancient and strong. There is just so much style in this game. Even the character animations show little signs of human frailty in the way your character stumbles.
