I haven't seen anyone mentioning this gem:

Vampire Survivors

Minecraft. It's just a nice game to get lost in.

For me, it’s always Ocarina of Time. The music always improves my mood and there is something oddly comforting about the game.

OpenTTD is my happy space. It's relaxing to just hop in and start building some railroads.

Try not to have an overly rosy retrospection about this. There were plenty of crappy, cash-grabby games in decades past. We just don't remember them because they were crappy, cash-grabby, and not worth remembering. They hadn't invented microtransactions yet, but that's just one more flavor of crappiness.

I can always go for a game of Age of Empires 2. That game takes me back to my childhood.

I'm surprised Katamari Damacy hasn't been mentioned yet. Both that game and its sequel, "We Love Katamari," have been remastered in recent years (in fact, the sequel just came out last week) and they're a joy to play.

The game has all that OP mentions... Quirky art style, awesome music, simple tactile gameplay, and just overall a relaxing and fun time.

Journey and Flower

MH Rise (Lance for tank mode) - fighting Melvor - idling Disney Dreamlight Valley - collecting Hardspace Shipbreaker - dismantling

It has been a while, but there was a time when, if I was feeling really anxious and almost panicky, a quick playthrough of Enter the Gungeon would chill me right out.

Unraveled (Unraveled 2 is great for 2 players, too), and Hue. Then there's always Slayaway Camp. All good on Steam Deck as well.

But those are for the times when I'm not addicted to RL.

Stardew Valley is my go-to. I found Firewatch really easy to get lost in too.

Anyone of my simulation/management games. Whether it's running a hospital, creating an auto manufacturing assembly line or helping some brave adventurers find oxygen I'm always more at peace with a single player goal driven experience.

Euro Truck Simulator/American Truck Simulator

It quickly just becomes a virtual road trip simulator, and as someone who generally enjoys driving and road trips its very chill

I could (and have) spent hours in Valhiem just noodling around surviving as a Viking

Tetris 99... somehow

Stardew Valley is amazing for this. Minecraft was it for years and years, but Stardew is just like a nice hug. I adore it.

Hogwarts Legacy has also fallen into this category for me now.

Jump Ultimate Stars.

I'm probably the only one left still obsessed with Nidgogg 1.

Chrono Trigger. Always feels like being home with old friends. A joy every time I playthrough

TES Oblivion and Sonic Adventure 2. SA2 was a childhood favorite I got very good at, and the extra mission, game modes, and pet sim aspects makes it fairly re-playable without having to start a new game file. Oblivion is just whacky and fun, and if you know how to exploit mechanics you can get up to some pretty crazy stuff in a matter a minutes after starting the game. While grinding skills could be seen as... Well a grind, it's a grind I personally enjoy. Both games let me dive straight into what I'm feeling like doing, and reward mastery (even if one of them is cheese mastery).

Oddly enough I go through phases where I just level up a character on WoW. It's mindless for me and I can just zone out and watch TV while playing.

No Man's Sky is a good mix of nice scenery, low stress, and engaging without requiring a lot of mental capacity that can be comforting.

Trackmania 2020 is great!

Morrowind and Mario Maker 2.

Star Wars: Racer - I know every track by heart at this point, have it on my Switch and still play quite a bit. Amazing flow state game.

Rollercoaster Tycoon 2 - absolute classic and the nostalgia I get from playing is unmatched

Age of Empires 2 - the music is just muah

KotoR - Best Star Wars game ever made next to Dark Forces 2 and Jedi Outcast

Deus Ex, Vampire: The Masquerade: Bloodlines, and Cyberpunk 2077. Like you said, they are games I like to get lost in, just walk/drive around in, soak in the ambience. I like to pretend I'm there; it's a great escape, like you said, comforting.

As others have already touched upon, I think the Zelda series is masterful (pun semi-intended) at this.

I can't count how many times I've replayed through Ocarina of Time just to relax and vibe. These games really excel at creating little moments of catharsis.

I used to spend hours in OOT just hanging around Kakariko or Lon Lon Ranch or soaking in the ambiance of the Forest Temple.

Or hanging outside the Stock Pot Inn in the morning, waiting for it to open in Majora's Mask.

Or floating around on the Great Sea in Wind Waker.

Or taking Marin down to the beach in Link's Awakening.

And so on, up through the BotW/TotK era.

Slay the Spire is a big one. Casually smacking out wacky runs during a lunch break is the bee knees.

Brotato is good for this too, even if the game can be a bit repetitive. I wish it would grow even bigger with more items, more deep mechanics, more everything. Thank goodness there's modding.

As a kid, Alien versus Predator co-op survival maps were a big one. Mindless mayhem clears the mind like nothing else.

As silly as it may be, city builders or transport managers. I find it very relaxing and easy to just lose a day a in. I usually play with sandbox modes because I just like to design. It's kind of like digital model building I guess

Outer Wilds. But I already know everything that happens. So I prefer watching a stream/VOD of someone playing it for the first time.

Tropico 6, Cities Skylines, or any city builder. Planet Zoo once I get a less potato PC (CS too). I'll load up a sandbox map and build. And if I need to get up for any reason, I can hit pause.