the King of this genre, is the more than likely the TouHouh series of overhead shooters.
These games DEFINED the term "Bullet Hell"
Easily my favorite is Touhou 9 -
Phantasmagoria of Flower View,
which is a 2 player VS type game
It's a pretty amazing game, and the only one of the series that takes to ENB pretty well
This uses Bloom,a Color correction palette, and a Modified Guilty Gear Effect.txt (which is what makes this mod worth while) , all of these elements add more color contrast, and smooths out all of the digital edges. The bloom kicks up more against darker stages, and it backs off on the brighter ones, and really makes some of the crazy attacks stand out without getting in the way .
( it took a day before I realized I forgot to add the Effect.txt, sorry to that 1st guy who downloaded it LOL)
Untitled-1 by captainskullsaber, on Flickr