Phantom Dust.
The Trailer (Hope you like anime):
And the second Trailer which shows off more of the characters. (I always playyed Sammah online, the dude with the tie and sunglasses)
Published by Microsoft and developed by Yukio Fatatsugi, the mind behind Panzer Dragoon, Phantom Dust was a first-party budget title for the original Xbox that never the less managed to be awesome, addictive and to this day unique. I've never seen anything like it to this day and that saddens me greatly. Essentially a mix between third person action and a collectable card game it was equal parts reflexes and strategy, any fan of fighting games would love it. If you like anime then tack that on as an additional bonus point. The single player campaign was pretty memorable, the characters existed in a world that had been ravaged by an alien dust that stole the memories of anyone who stayed in it too long, monsters were born from the dust but a few survivors could use it to turn thoughts into reality, an ability that lent itself naturally to combat. Speaking of which it had insanely fun multiplayer, the netcode was great and matches could be played as free for alls, 2 vs 2 battles or even 3 vs 1 matches. Players built up an arsenal of skills bound to the face buttons with a wide range of effects and types (your deck), balanced this out with energy particles (used to power your abilities) and then went to war in multi-tiered arenas, throwing each other through bill boards and collapsing highway overpasses like an episode of DBZ without all the chatter.
Screen Shots:
SOUNDTRACK:
The music also deserves a mention, a lot of it done by Yuko Araki (Cornelius, Mi-Gu) featuring some sweet original tunes and remixes of classical music. It's an interesting range but I always liked it, sets the tone of the game well too. Some of it reminds me of Nujabes' Work.
A game sorely in need of a remake or sequel.