A few more ideas:
Guild Wars 2. Their proclaimed "painterly" art style is positively gorgeous. The textures are top-notch and colorful, and the world feels alive and vibrant, moreso than most. It truly is a thing of beauty.
Magic: the Gathering. Sure, the graphics may not be as flashy as some, but the art is truly magnificent: simultaneously epic and tiny, grim and silly, hideous and beautiful, logical and abstract. Few other games can boast such diversity. (What? you didn't say video game, did you?)
Minecraft. I think Gavin "Miracle of Sound" Dunne said it best [http://www.escapistmagazine.com/videos/view/miracle-of-sound/3009-Mining-All-Day-long]: "... I start to see the world in grey and blue and brown and green. These pixels are so simple and so beautiful and clean. And I feel good cuz' I've been minin' all day long."
Odin Sphere. A pioneer of the 2D sprite brawler, so full of life and color, but retaining its otherworldly style; a caricature of real life.
Final Fantasy 7. Top-notch visuals for its day, but the enduring parts are its themes of love and loss. FF7 takes the inner identity crises that stem from personal loss, trauma, and horrific tragedy and externalizes/explores them in ways only a video game can. (and the music... dear God, the music... I still well up a bit to Aeris's Theme.) Still a beautiful game at its core, despite not having aged well graphically. (Similar, but less game-specific praises to the other classic Final Fantasy games of the SNES and PS1 eras, some of which still hold up today.)