This has been around for a while, but it's worth mentioning here for two reasons: one, it's awesome, and two, you can now buy the full version for a mere US$10. With its gorgeous artwork, relentless pacing and liberating controls, Noitu Love 2: Devolution is well worth that asking price.
It's the novel control system that truly delights. Left and right movement is via the keyboard, but all attacks are delivered using the mouse. Click on an enemy and you'll dash towards it; keep clicking on new enemies and you'll chain together a sequence of sustained mid-air attacks. Further, once you've completed the 2-3 hour game, you unlock a new character whose attack mode is different, allowing you to lock-on to multiple enemies before firing - kinda similar to the likes of Rez or Panzer Dragoon, but still all in the confines of a 2D platform space. I understand there's a third character to unlock once you complete it a second time, but I haven't got that far yet.
Check out this trailer and then pop over to developer Joakim Sandberg's website and give him some money for being so awesomely talented.