I know you said 2004-2005, but I can't help resisting to offer this. Sikendensetsu 3 (part of the secret of mana series) for snes. Its a japanese game, but the rom has an english patch. It has beautiful graphics (better than chronotrigger I think), can pick a party of 3 out of 6, and depending on how you pick it it drastically affects the story. Its an action rpg, with the melee attacks done in real time while the magic and summons are turn based. The game has a good story and is looong (it took a friend and I 40+ hours to beat it I believe). Its free now since its not in circulation anymore :), and depending on the emulator you can coop with upto 2 other players. The best emulator zsnes only lets you play with one other friend online. Btw, when you first load up the game in the emulator it'll look ugly, play around with the graphics settings and you can make it much more stunning.
Btw Jep, Halo pc doesn't have mp coop

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