I can't really name a single one that would be THE one. But the one I returned to the most over the years was the original Dragon Quest Monsters.

I had it on my Game Boy since I was in elementary school and even then played through it multiple times. Later I played through it multiple times on emulators. I just love this game so much.

It has a lot of flaws, starting with the limitations of a Game Boy game, but later games and other monster collectors never captured my heart like this one did.

@GeekFTW Duck Hunt and Zelda A Link to the Past on SNES. Core childhood memories with family.

Duke Nukem 3D

Dishonored, I absolutely adore that game, and it still looks so good because of the art direction they took with it. Funny enough, it was the same art director as Half Life 2

Definitely Dark Souls. I have played DS 1, 2, 3, Bloodborne, Elden Ring, and Sekiro. I only have completed DS 1 and 2 out of them (mostly due to time, with the exception of 3 which I just don't like).

I know the DS1 map like the back of my hand, the mechanics feel natural to me, I feel like I'm being treated fairly and have the skill to complete challenges, and it genuinely feels rewarding for me. I feel good after playing Dark Souls for a bit. Even when struggling with a boss, 95% of the time it felt like I had made a mistake which could be fixed next time.

I’m probably weird when I say Final Fantasy XIV A Realm Reborn. At first a failed game that became a labor of love by the people that took it over. It took multiple years and expansions for it to come to a “conclusion” and the once i finished it, I was very satisfied.

To me it’s similar to the Marvel project up until the conclusion of the Thanos arc. I’m not the biggest marvel fan or much of a Disney fan. I do really respect the courage it takes to throw that many years at a project and trust it almost all the way.

FFXIV feels like that. It has that final fantasy marriage of interesting yet somewhat complex story with a message that makes you think. Its an MMO but honestly you can enjoy it up until the conclusion of End Walker with a couple of friends and some queuing up for the story fights. You shouldn’t have to do any terribly difficult encounters to progress the story and experience the game unless you choose to. The. Every so often you run into a song and get blown away. The game does a great job of usually having each expansion have a visual and music theme and sticking with that without making it feel like repetitive copy paste job.

I almost never like replaying a game or heck rereading the same book. But this game is the one exception where if a friend finds interest, I’ll resub and level yet another job with them and totally enjoy all over again.

Gothic I&Ii

Gotta go with Morrowind. It was a pretty formative experience during my early teenage years, and it's one of the few that I boot back up for a fresh run about once a year. Instigating the downfall of the Tribunal has become something of an autumn ritual for me. I know the world map layout of Morrowind better than I remember the layout of some of my own childhood homes.

It's a little clunky and not enjoyable for a lot of people that jumped into Elder Scrolls with Oblivion or Skyrim, but for old school fans, it's still probably the single greatest product that Bethesda has ever released. Fallout New Vegas makes a close second place on that list, but at least in my opinion, Morrowind holds the crown and given modern Bethesda's tendencies I don't expect that to change.

Red Dead Redemption 2 with zero hesitation; honorable mention to Skyrim.

It might sound dumb, but Guardian Tales. It's a gacha game on mobile and Switch, but I really love it. The story is great, it's fun to play, and the devs are very generous. I've played it multiple times on different accounts just because I have so much fun with it.

What a tough question to answer, stretching all the way back to Atari 2600 for me.

I think I'll pick No Mercy/Virtual Wrestling Pro 2 on the N64. Possibly thousands of hours both solo and competitive at a friends with some incredible round robin tournaments with up to five participants. Just amazing Create A Wrestler and one of my handful of favorite gameplay mechanics ever. Also we were paying during the exciting days of pro wrestling so we had that enthusing us as well.

THPS2 and a close one is F.E.A.R.

Trials of Mana. Actually the whole Mana series were completely unique and very innovative when they first released. But the combination of story telling, party building, and combat system still hasn't been topped for me. The games are something I always have ready to emulate at all times. Fingers crossed they decide to remake the rest of the Mana series. Legend of Mana needs some love even though I remember most people weren't really keen on building their own world.

The Tales series was probably the closest before the switched from 2D to 3D. The switch, I thought, took away a lot of what made them stand out from other jrpgs in the market.

My close 2nd is Legend of Dragoon since it actually changed the combat system in a really meaningful way. Legend of Legaia also did something similar but I thought the storytelling was better in Legend of Dragoon.

Soul Sacrifice still needs some love. It's only downfall was releasing on such a niche system like the Vita. It actually moves the MH formula forward in a really interesting manner by forcing you to make really interesting choices in the story.

Stardew valley was a really fun game to play with my wife

"Little Big Adventure 2", also known as "Twinsen's Odyssey" in the US, and rebranded worldwide as "Twinsen's Little Big Adventure 2" few months ago.

Super Metroid is the GOAT

Super Mario Galaxy 2 and Skyrim

Undertale still holds a special place in my heart after all these years.

It made me care about its characters in a way that no game had ever done before, and few have since. The cool and replayable story, along with a great soundtrack are other things that I like. Only criticism I really have of the game is the questionable graphics, but I've never been the type to care too much about graphics anyways.

Going all the way back to the NES for me, and I'm getting the feeling I'm quite a bit older than most of the commenters here: Super Mario Bros. 3 - best game of all time. :)

Fallout New Vegas

Dead by Daylight. I love it as much as I hate it.

For myself: Illusion of Gaia (SNES).

I hear a lot of people talk about Soul Blazer and Terranigma when talking about this trilogy but IoG was always my favourite. I still have the soundtrack on my phone after all these years.

Like some already said, I too love Mass Effect, Dragon Age, The Elder Scrolls, Zelda TP and Stardew Valley. It's hard for me to chose a favorite game… There's a few of them I equally like, and it kinda changes depending on my mood.

Saints Row 2 is one I haven't seen mentioned yet. There's always something fun to do in this game and it’s hard to get tired of it. The map is packed full of interesting stuff, feels bigger than it actually is. And without writing a novel about it, I like the story a lot. It's a perfect balance between wacky and serious, plus the characters are great. Truly underrated game imo. Shame what happened to the series…

As I've gotten older and have less time to commit to competitive gaming, cooperative gaming still lets me enjoy challenging multiplayer experiences without having to worry about ELO or keeping up with the current meta as much.

As much as I love Helldivers (and I am very excited for the sequel coming out later this year), Deep Rock Galactic is undeniably the champion of the cooperative gaming genre. You can jump into almost any lobby of random players and be rocking and stoning together instantly. Deep Rock Galactic features many game mechanics that just naturally result in cooperative play, without the need to rely on voice or text communications (though, voice and text are available and used).

Not to mention that the devs are really really amazing. Seasonal updates always come free of charge. They have a battle pass system that is 100% free that just rewards cosmetics. If you don't get battle pass cosmetics by the end of the season, you can still earn all the cosmetics at a later date. The only DLC on offer are cosmetic packs, which are really cool, but the cosmetics you can earn in-game are also really cool. There's no pressure at all to spend more outside just buying the base game. I deeply appreciate them and how they conduct business.

Streets of Rage 2. Favourite soundtrack, too.

That Dr. Mario vs Tetris game. My mom would bust it out and we’d have competitions way past bedtime because she was addicted. So some good childhood memories attached to a fun little game.

Star Control 2. My son and I just started another playthrough.

Being totally honest, I don't think I can just settle on one game like that. I play different games for different reasons, and what genre/titles I've played the most has varied a lot throughout my life.
Up there, however, is Dark Souls, as well as League of Legends (despite all the issues I have with it, it's sucked me back in for over a decade now).

I always end up going back to the first Half-Life; everything in that game is very well made.

Final Fantasy VII

While it's hard for me to come up with an ALL TIME favorite... playing Doom 2016/eternal is one of my greatest pleasures in life. Just simple mindless hack and slash that can get MUCH more difficult if you want it to

Castlevania Symphony of the Night. Had no idea what I was getting into and have been chasing that same experience ever sense.

Holiday Island. And Transport Tycoon Deluxe...

GOAT is Dungeon Keeper. Holy siht that's a great game. Still play it to this day, despite the fact that it's close to 30 years old.