Pokemon.
Wasn't very popular with the other 15 year olds.
There are far too many people who play that game. Hell seems a good deal of the people that I played FFXI with play Pokemon like freaks (they are all adults pretty much too lol). Same crowd who played Magic the Gathering and POGs at the local bookstore. I never got into any of those things. Dungeons and Dragons required so much more imagination that it shit all over Magic the Gathering and Pokemon and other card games.
PC: Elder Scrolls II: Daggerfall wasn't too popular with my friends (it intimidated them). Being a vampire in that game was wtf hilarious, I would ride around on horseback cutting people's heads off. Ultima: Underworld was also pretty sweet (omg 3d RPG). Hexen, Heretic and Heretic 2 were all good games. Total Annihilation was a good game with tons of units and a 3d battlefield. Myth had 3d battlefields and was badass due to Bungie's physics that were ahead of their time imo (dwarven satchel charges rolling back down hills and blowing up my troops was hilarious). Homeworld was just plain awesome (omg strategy + SciFi space game of doom). Planescape Torment: Morte owns your face and your soul (gotta love disembodied skulls that bite enemies and make me laugh with good dialogue). The Marathon series (really Macintosh though), Bungie's foray into FPS. Battlezone was a good game if you are talking about the 3d RTS type game (and not the original vector game). Crusader: No Remorse was good. Xcom was pure win (fuck the aliens in that game sometimes). Urban Assault was similar to Battlezone to me. Descent: Freespace (best giant spaceships in a video game ever). Really I played way too much fucking Starcraft and Unreal Tournament for my own good (those are far from overlooked games). Same goes for the Baldur's Gate games imo, played by most people I know (Icewind Dale wasn't bad). Really it could go on forever with PC games... Dark Forces games were good especially the first couple of Jedi themed ones (force choking people ftw). I liked Rise of the Triad because it is fucking hilarious mainly (WHOOPSIE!). FFXI and City of Heroes are somewhat overlooked MMORPGS imo (Star Wars Galaxies was crap lololol). Everquest 2 has made some strides to make it a good game as well. The Lucas Arts adventure games were win, the last Monkey Island and Grim Fandango were overlooked compared to earlier releases (WTF happened with the recent Sam and Max?). I played a good deal of Willy Beamish sadly (Kings Quest IV needs to disappear). I liked almost all of the Mechwarrior franchise games.
Xbox: Chronicles of Riddick: Escape from Butcher Bay: Not that many people played it that I know. It was a very good game and probably the only movie licensed game that was actually better than the movie. Stealth elements with hand to hand combat combined with FPS gameplay made for an interesting game. Ninja Gaiden (Xbox version): This was too difficult for most people I know and not that many played it at all due to it not being for PS2. This was the last game that made me throw a controller. Beyond Good and Evil: fun game that for some reason got overlooked same, goes for Psychonauts. The 2nd KotoR wasn't bad (HK-47 made the first along with making the wookie kill Mission Vaio lol... well triple double cross murder was fun), playing as a Sith was 100 times more fun. Jade Empire was also a fun game with its fighting elements and Bioware's first real IP. Mechassault 2 had so much promise but was a fun game multiplayer even with its faults control wise.
PS2: Nothing lol. Disagea maybe, that system had so many games though. The last Onimusha game was fun. I beat so many games for this system either on rental, borrowed from a friend or just plain sold back to EB it is disgusting. The first Dark Cloud was pretty good. Xenosaga III was a solid attempt at redemption imo (1 and 2 were subpar).
PS: Grandia, Suikoden II, Vagrant Story (well most I know don't have it yet alone have played it). Xenogears is rated high but most people don't have the patience to play a RPG like that. Bushido Blade was good and had somewhat realistic weapons (one hit kills basically). Brave Fencer Mushashi was pretty good.
Saturn: Panzer Dragoon Saga maybe as any Saturn game seems overlooked to me that is a good game. Rondo of Blood: Castlevania. I guess you could include a shitload of 2d fighters as well since the Saturn was so good at running them. 4 player Bomberman lol. We sold this system and its games to get a N64 on release (me and my brother).
Genesis: Phantasy Star 3 wasn't that bad of a game, the entire franchise is overlooked imo due to the way it went in the multiplayer direction versus trying to directly compete against the Final Fantasy and Dragon Quest series as stand alone single player products with a story that was somewhat decent (PSO and PSU have a crap story imo).
NES: Battletoads: fuck that game rofl, that bike level needs to die in a fire. The first TMNT game was hard as fuck too. Golgo 13 (spelling) was a fun game for its time. River City Ransom was fucking win as a RPGish sidescrolling fighting game. I actually liked the second Zelda game and Simon's Quest wasn't that bad to me (though seen as crap by a good deal of Castlevania fans). I actually first played an Ultima game on this console and not on PC. Ikari Warriors was good as competition to Contra. Skate or Die was a fun diversion.
SNES: My favourite console of all time (not counting PC). Actraiser: Beautiful musical score combined with a god game and sidescrolling action game (though the action elements were admittedly pretty basic). Really too much to name. Could get scary like the PC games list. People blow their load over Ocarina of Time (rightfully so) but Link to the Past was great. Super Mario RPG was from what I understand Square's swansong with Nintendo and also a great game. I played the living shit out of Pilotwings just killing myself over and over. This system gets pimped enough probably (Star Fox, the best of the FF franchise, FZero, Mario Kart, Donkey King, etc will do that).
Dreamcast: Skies of Arcadia and Grandia 2. I played the fuck out of Power Stone, Soulcalibur and the NFL games multiplayer with my friends. Those really can't be considered as overlooked. Metropolis Street Racer was fun, and a precursor to the Project Gotham Kudos style points racing games. 24 Hours of Lemans was fucking insane and needs to die. Fire Pro Wrestling (Japanese import onry) ridiculously huge movelist and insane customization. Giant Gram (also JP onry): WTF hilarious announcing with a fairly free flowing counter and grappling system (PILE DRIVAHHH!). Legend of Kane: Soulreaver was cool too with whole sucking in souls thing.
N64: Conker's Bad Fur Day: Just fun as hell with a weird sense of humor that tried to be somewhat adult, the Xbox version had decent multiplayer imo. Paper Mario was fun as an attempt to resurrect Super Mario RPG in a way. Banjo Kazooie: None of my friends played this or the Rare Donkey Kong games for some reason (probably because they are lamers who whored the fuck out of Goldeneye and Perfect Dark until their eyes bled). Action Adventure games are fun to me.
360: Ninety Nine Nights is a fun Dynasty Warriors kill hundreds of people at a time type of game. Kameo: Elements of Power wasn't bad and actually fun if you get used to the control scheme. PDZ sucked balls imo though. Crackdown was fun and really worth playing even though it came with Halo 3 beta. It is like GTA but you are a bioengineered cop (who is free to kill anyone he wants up to a certain extent). The 3d landscape is what makes it amazing and the ability to scale the side of 100+ story skyscrapers and jump rooftop to rooftop murdering people. It has a RPGish system and my grenades happily have a blast radius that makes them unsafe to use as they kill hundreds of innocent people and other police (wee run around while on fire screaming bitches). Throwing cars with criminals in them (before they can get out) off a bridge while they scream falling to their doom is also special stuff. The body juggle and car juggle acheivements that require you to juggle with 6 rockets are also awesome. Co-op multiplayer over Live with my FFXI friends sealed the deal.
Gamecube: Eternal Darkness: Sanity's Requiem... fucking insane game with crazy Necronomicon influences and a decent survival game to boot. Getting Silicon Knights was a good move imo for Nintendo even though it didn't translate into sales. I liked the FZero game Sega made for GC though it was hard as hell. Paper Mario: The Thousand Year Door was also fun, playing as Bowser is priceless. Tales of Symphonia was pretty cool and the girl turning into an angel was interesting in how it was gradually done with her progressively not being in the material world (Kratos is a bastard though).
I include some fairly popular RPGs just due to most people being asshats and playing too much Madden and FPSes. Well that and Super Smash Brothers, Soulcalibur 2 and 3, Guilty Gear, Tekken and various other fighting games as well. Those seem to get whored out big time by my friends as they are more social than single player games.
Screw my old Tandy, Texas Instruments (basically same as Tandy), C64 and Atari days. Those games were shit even though they were somewhat fun for their time. I had a soccer game, a football game and baseball lol. I never got to play Adventure or M.U.L.E. sadly. My grandfather had a Phillips CDO, all he had was Mountainclimber and Lemmings though.