The storyline for the game is based loosely on the "Fatal Attractions" crossover story published in 1993 and which ran through all the X-Men universe titles of the time. All of the published issues (X-Factor #92, X-Force #25, Uncanny X-Men #304, X-Men #25, Wolverine #75, and Excalibur #71) are collected in a trade paperback, but unfortunately they don't feature the holographic insets the original prints had in their covers.
Despite what everyone else tells you, X-Men: CotA was developed by Capcom, released in arcades by Capcom, but wasn't ported to home consoles (except for the Saturn version) by Capcom. Acclaim and Probe handled ports to the PSone and PC, and Acclaim published the Saturn version for Capcom.
This was first released on the Sega Saturn Platform
Included as a secret character is Akuma, one of the baddies of the Street Fighter series. (an omen of the future Marvel/Capcom crossover games?)