The Voice of Cards games. I love the aesthetic of an entire virtual world represented with cards
The Guacamelee series - Never played anything that looks like them. Vaguely reminds me of Samurai Jack
Cris Tales looks amazing and does fun stuff with its time travel gimmick
Ska Studios games - Dark, weird, and distinct
Lost in Random and Pumpkin Jack - Tim Burton-esque
Viva Pinata - Lush, gorgeous, vibrant visuals with a really unique twist on "animals"
Valkyria Chronicles - The water color, interactive, story book look
Anything from Team Ico has a distinctive look
Of course Journey - The heavy use of moving tapestries everywhere and unusual looking main character
Dust an Elysian Tale - One of the most beautiful games ever made
Bye Sweet Carole, which hasn't released yet