Truly iconic games, in my opinion, especially at the time of their release:

The original Mario Bros for the NES
Mario Bros 3 for the NES
The original Sonic for the Sega Genesis
The original Mario Kart for the SNES
Street Fighter 2 for the SNES
The original Donkey Kong Country for the SNES
The original Resident Evil for the PS1
Final Fantasy VII for the PS1
Metal Gear Solid for the PS1
Mario 64 for the N64
Zelda Ocarina of Time for the N64
Resident Evil 4 for the GC/PS2
The original Halo for the Xbox
GTA 3 for the PS2

Stopping for now, there are many others.Most of the games I listed above changed gaming in some way so they deserve 'legendary status'

If that first list would be also someone's favorite games list...

The legend of zelda Twilight Princess.

Metroid Prime

Xenoblade Chronicles

Donkey Kong Country Tropical Freeze

Forgotten hope 2 (Its a mod to battlefield 2, but preatty much its own game)

Supreme Commander Forged Alliance

The obvious reply would be Ocarina of Time, Shadow of the Colossus, FFVII, Chrono Trigger etc. But those games are all ready considering legendary even by the main stream. I think the OG question was probably lined up at games that are underappreciated by the masses but should receive legendary status...here is my list.

1.Alundra
2.Lunar 1 and 2
3.Xenogears
4. Majora's Mask
5. Tales of Vesperia/Legendary
6. Grandia 1-2
7.Star Wars KOTOR
8. Skyrim ( it's on every platform and Bethesda has earned a lot of critics but this is its best game)
9. The Last of Us
10. Resident Evil Code Veronica DC version.

11.Skies of Arcadia
12. Record of Loss war.

God of war
God of war 2
God of war 3
Uncharted 2
Uncharted 4 with lost legacy dlc
The last of us
Smash bros 64
Pokemon gold and silver
Mario kart 64
Dragon age origins
The witcher 3
Horizon
Killzone 2
Fallout 3
Star wars battlefront 1 and 2 originals
Dragon ball z budokai 3 and tenkaichi 3
Crash team racing
Im tired of listing lol

Above Legendary Status:
Club Penguin

Legendary Status:
Super Mario Bros.
Donkey Kong
Pac-Man
Tetris
Mario Kart 8 Deluxe
World of Warcraft
Grand Theft Auto V
Pokemon Red and Blue
Minecraft
Fortnite
The Legend of Zelda: Ocarina of Time
The Legend of Zelda: Breath of the Wild
The Sims 3
Final Fantasy VII
Earthbound
Super Mario Galaxy
The Elder Scrolls V: Skyrim

And then other games that either come extremely close or its just too early to say:
Super Smash Bros. Ultimate
Spider-Man
Red Dead Redemption 2
Wii Sports
Pokemon Black and White
Splatoon 1 & 2 (I consider it a single entity)
Mario & Luigi: Bowser's Inside Story
Chrono Trigger
Mario Party 2
Sunset Overdrive

Here are the games with "legendary status" in my books.
- Grand Theft Auto series (excluding IV)
- The Elder Scrolls V: Skyrim
- The Legend of Zelda: Breath of the Wild

and thats it. There are plently of amazing games out there, but these three take the cake, imo.

final fantasy 6 + 7, both jrpgs with an amazing story and many moments you will never forget, ff6 with the opera scene, ff7 with the death of aerith

See the Top 50 thread's final ten days.

Some pretty obvious choices in my list but hey, they are legendary...

Legend of Zelda - link to the past, ocarina of time and majoras mask
Resident Evil 1,2 and 4
Super Metroid and Metroid Prime
Super Mario Bros 3, Super Mario World and Super Mario 64, Galaxy 1 and 2
Yoshi’s Island
Castlevania-Symphony of the night

(Feel like I’m overlooking something but these are probably my all time favourites)