Mainly because it has a very unique art style that spell “artsy” and, I guess, “stylish”. Imagine if Bones — the anime studio responsible for certain blockbusters like Fullmetal Alchemist, Eureka seveN and Cowboy Bebop the movie — made a game thanks to Sony’s huge checkbook (or something) and you’ll probably have something like Gravity Daze.
The game is actually being spearheaded by Keiichiro Sotoyama, the creator of Siren, in case you’re wondering. Couldn’t really comment on that because I have not played any of the Siren games.
In any case, the visuals are just splendid to watch, and I’m pretty positive you’ll know what I mean once you see this clip:
…and here’s an 8 minute gameplay footage: