Winning the game on Nightmare unlocks Hell mode and winning it on any difficulty unlocks KUN KUN!!!! Objectively it's the best game ever. Remember to use Windows XP compatibility mode for Versus mode to work!

2D fighting game with 9 characters to choose from and a story mode.

Bullet hell game that I couldn't get to open. Probably needs a VM.
15citron website

You go and slash vegetable...thingies WITH a SWORD

Another fighter fangame

Rozen Maiden buddy for your PC! Use this command on lanix to make it work:
wine regsvr32 comdlg32.ocx