For that one, Marvel decided that instead of licensing their universe to an existing RPG company, they'd contract a company to develop an RPG for them, which they would then own the rights to. The odd thing was that the company they contracted wasn't an RPG company. The result was an interesting diceless system, using resource allocation for conflicts... but one that wasn't intensively playtested.
Marvel also kept the project pretty much under wraps until close to completion, and then sold the game directly through comic distributors. It seems to have sold reasonably well for a non-D&D RPG - but Marvel had been anticipating that it would sell as well as D&D or their own top-tier comics. It went through multiple print runs, but Marvel still killed it after less than a year, considering it a failure. Only two of the four announced supplements were ever released.
Chris - which superhero game don't you collect? Wondering because I also collect them!