Before your head explodes, no, this game isn't a planned release, commercial or non-commercial, for the DS. Card Sagas Wars is a homemade PC project created with M.U.G.E.N, a "freeware 2D fighting game engine." The music and backgrounds have been ripped from a variety of popular games, but it looks like the character sprites have been redrawn for a consistent (and totally awesome) look.
If anything, Card Sagas Wars' developers are ambitious, setting out to include a collection of playable characters that would put even Super Smash Bros. Brawl to shame, its posted list of 995 "Blue Series" cards ranging from Killer Instinct's Cinder to Castlevania's Soma Cruz. A demo with four playable fighters is currently in the works, but no concrete date has been set for its release. You can see an older, less epic trailer for Card Sagas Wars past the break.
[Via Indie Games]