So I am just now become aware of Zineth, a proof of concept game done in Unity by some aspiring young developers who call themselves Arcane Kids. I'm currently playing the demo and really enjoying the speed and JSR-like atmosphere of the whole thing. It's got a ways to go in terms of polish, but the underlying idea is cool and the game is definitely worth a try. It's a svelte 40MB download, available for Mac and Windows.
Gameplay Video
Official Site
Gameplay Video
Official Site