A lot of the sames I know and love are unknown and unsuccessful because a lot of my games were fished from bargain bins back in the day XD
The most unknown game that I absolutely adore is: "Skullmonkeys". "Skullmonkeys" is a platform sequel for the point-and-click puzzle game "The NeverHood" for the PC. Because a lot of PC gamers don't play on consoles, it was really ill-advised for Skullmonkeys to only be available for the playstation =\ but anyway, it's a really quirky and funny game that's completely "Klaymated" (their words) about Klayman who is brought to the planet of the skullmonkeys when the evil Klogg (who is technically Klayman's brother) crashes on the planet and immediately becomes the king of the skullmonkeys. He's brought there to liberate the skullmonkeys (who don't really want to be liberated) but since Klogg is building a machine to destroy The NeverHood (where Klayman lives) he'd have to be there anyway.
It's a really good game and a rare find, since the company that made it is now defunct and thus the game is no longer manufactured. That said, it's worth the money if you can find it. It is kind of terrifying, even though it's not a horror game. That might be me, though, claymation unsettles me XD
By the by, the game is done by the same guy who did Earthworm Jim games and the Catscratch cartoon.
The other games I love but no one has ever heard of are:
Hodj' n' Podj' (PC)
Oddballz (PC)
GearHeads (PC)
Creatures (PC)
A Boy and His Blob (NES)
Plok (SNES)
Smartball (SNES)
Ardy Lightfoot (SNES)
Claymates (SNES)
Donald Duck as Maui Mallard in Cold Shadow (SNES)
Young Merlin (SNES)
Digimon Rumble Arena (PSX)
Rat Attack! (PSX)
Space Station: Silicon Valley (N64)
Klonoa 2: Lunatea's Veil (PS2)
Okage: Shadow King (PS2)
And, like, many others I can't remember XD