Some sequels of games make previous ones obsolete, while some don't. For example, Super Smash Bros. Brawl is so good, in my opinion, it makes the previous two games obsolete and I see no reason to play them anymore. Whereas Mega Man 3 is not better than Mega Man 2, but they still both hold up as games I would go back and play. And of course there are some sequels that dont quite live up to the original.
Basically, these games "age well" and have a high replay value.
NES:
- Super Mario Bros. 3
- Mega Man 2
- Mega Man 3
- Dr. Mario
- Mike Tyson's Punch Out!!
SNES:
- Super Mario World
- Super Mario Kart
- Legend of Zelda: A Link to the Past
- Teenage Mutant Ninja Turtles: Turtles in Time
- Super Bomberman 2
- Donkey Kong Country 2
- Super Mario World 2: Yoshi's Island
- Super Metroid
- Legend of the Mystical Ninja
SEGA GENESIS / SEGA CD:
- Sonic the Hedgehog
- Sonic the Hedgehog 2
- Sonic CD
- Kid Chameleon
- Final Fight CD
SEGA SATURN:
- Mega Man X4
- Virtua Fighter 2
- Street Fighter Alpha 2
PLAYSTATION:
- Final Fantasy VII
- Street Fighter EX plus Alpha
- Super Puzzle Fighter 2 Turbo
- Castlevania: Symphony of the Night
DREAMCAST:
- Power Stone
- Jet Grind Radio
- Crazy Taxi
- Marvel vs Capcom 2: New Age of Heroes
- Street Fighter 3: Third Strike
- Bangai-O
- Sonic Adventure
- Chu Chu Rocket
- Tech Romancer
- Soul Calibur
- Street Fighter Alpha 3
N64:
- Mario Kart 64
- Legend of Zelda: Ocarina of Time
- Wave Race 64
- Super Mario 64
- Star Fox 64
- Mario Tennis
GAMECUBE:
- F-Zero GX
- Super Monkey Ball 2
- Viewtiful Joe
PLAYSTATION 2:
- Katamari Damacy
- Zone of the Enders: 2nd Runner
- Devil May Cry 3: Dante's Awakening
- Tony Hawk Underground
- Metal Gear Solid 2: Sons of Liberty
- Metal Gear Solid 3: Snake Eater
- Tekken Tag Tournament
- Jak 2
- Twisted Metal: Black
WII:
- Super Smash Bros. Brawl
- Legend of Zelda: Twilight Princess
- Wario Ware: Smooth Moves
PLAYSTATION 3:
- Valkyria Chronicles
- Metal Gear Solid 4: Guns of the Patriots
- Bayonetta
- Devil May Cry 4
- Uncharted 2: Among Thieves
- 3D Dot Game Heroes
XBOX 360:
- Gears of War
- Gears of War 2
GAMEBOY ADVANCE:
- Wario Ware Inc.
- Astro Boy: Omega Factor
- Puyo Pop Fever
DS:
- Mario Kart DS
- Advance Wars: Dual Strike
PSP:
- Yu-Gi-Oh Tag Force 4
PC:
- Plants vs Zombies
- Portal
