Guilty Gear X (Dec, 2001)
Published by Sammy Entertainment Inc.
Developed by
Arc System Works Co. Ltd.
Link at
MobyGames
The game is quite new, this is the official site:
http://www.guiltygearx.com/
But I can't understand Japanese!
Let me search better...
Edit: I've found only buy links for
Playstation2, PSP, Nintendo Wii, Dreamcast.
This is the only one I've found for PC (Out of stock):
play-asia.com
About Sammy Entertainment at
Wikipedia.
The company is affiliated to
SEGA Entertainment, Inc., so the game should be protected.