A few that I've really enjoyed so far, if you don't mind the suggestions:

* Antichromatic (hit and subsequently blasted out of the sandbox earlier this week, effectively Ikaruga mechanic applied to a platformer)

* Inferno & Ballistic SE (same author, same general gameplay, different world mechanics)

* Saturday Morning RPG

I'd love to see an actual vs fighter, but currently lack the free time to even care about hacking one up :/