Back when the Nintendo 64 was new and the Jag was still clinging to life, I was at CES. This would have been January 1995. Atari was flush with cash from a settlement with Sega, I believe over Atari's game controller patents. I asked the guy at Atari how the money from Sega was affecting their ability to market the Jag, and he just smiled and waved his arms around at the impressive booth.
I played some interesting games, but one that caught my eye was Phear, a weird game with a polygonal sphere over which the player dropped tetris pieces, trying to etch a hole in the core. It looked neat and moved smooth as a dream. It was never released, at least not for the Jag. Instead it came out a year or two later in a HEAVILY revised form on Nintendo's N64 platform. Rumor has it Nintendo saw it running in Atari's booth, walked over to the developer and offered $madcash for the rights to it. I sure wish I'd snatched that dev cart out of the Jag, it's a bit of history now.
I did manage to pick up a few copies of H2O's (the developer) promotional pages for the game. It's got spelling errors and is really pretty ugly, but it's basically the only lingering proof that the game was originally for the Jaguar. (update: that brochure is here)
Anyway, when it came out for the N64 it was pretty great. Nice colours, great music, and very decent gameplay. It was very much a zen game where you could play for a loooong time. It had multiple modes and two-player action, and it had 'cute little mascots' courtesy of the Nintendo influence.
I was a Jaguar fan, but even I can admit that this move was a good thing for everyone. Well, not Atari I guess, but when Nintendo bought the game they ensured it would reach an audience of more than six people.