Definitely check out Power Drive Rally on Jaguar. I loved that game. Great 2D graphics with solid/tight gameplay. If you like neodriftout, rc pro-am, super cars (amiga) it's a nice, relatively unknown, under appreciated game.
Rayman's nice, but can be played on other systems (ps1 & saturn?) There's also Raiden 1 on the jag (pretty nice).
On the 3DO, all I *really* played was Super SF2 Turbo, Samurai Showdown 1, Starblade and Road Rash. However there are better options for SSF2T and SS1 these days. Other notables on 3DO, but not all that great (just fool around for 30 mins then forget about it):
1) JPN YuYu Hakusho (2D vs fighting, would rather play the JPN megadrive versions)
2) JPN Sailor Moon (2D vs fighting, pretty weak)
3) JPN Ultraman (fmv gimmick stuff)
4) Twisted (gameshow, the early 'party' games)
5) Johnn Bazooka tone? or something like that... also on ps1/saturn
6) Starblade, now I really dug this rails arcade shooter (dumped quite a few quarters into it at Circus Circus Las Vegas) but it's also available on the ps1
7) Need for speed, was cool for it's time
8) Mad Dog McCree, never was my cup of tea but lots of kiddies at the time loved it
9) Gex, good but available elsewhere too
10) Starcontrol, I was biased (would rather play pc version at the time)
Regardless, on either system you're hard pressed to find more than a handful of solid games you'll probably play. If you don't already, I'd say track down JPN superfamicom gems or even ps1. Of the "obscure sfc/ps1 good game lists" I've seen here, people leave out quite a few titles I would add.
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