For me: Easily Portal 2.

A deeply rich story, funny dialogue, and great puzzles that will truly make your brain think. The story is very rich and spans across several different eras of Aperture history, going as far back as the 50s. The dialogue is funny and some of the lines are the most memorable in all of gaming (like the Cave Johnson lemon rant). And last but not least, the puzzles are great. They start off pretty simple, but as you progress further in the story, they get more and more complicated, especially when you get the repulsion gel and proposion gel. I feel like Portal 2 is the Gold Standard for puzzle games that every game that comes after it will be judged on.

Also, if you don't own Portal 2 yet, now is a fantastic time to get it - it's on sale for $1 on Steam, same with Portal 1. And if you want both games, the bundle containing both games is $1.50. Do not miss out on this offer, it's so worth it.

Stardew Valley.

Its revolver has continuously released huge updates for free and has commuted to never charging for dlc.

The games mechanics are pretty great and nothing in the game requires too much grinding to get.

Even when you “finish” the game, there are still things to do and starting a new files is always fun.

The characters are all great and have unique personalities. It really makes you feel like you are part of the town.

My wife and I have over 400 hours on a single file. It’s also enjoyable starting a new file. I like to challenge myself to see how quickly I can do certain objectives in the game.

It’s also decently cheap and has a huge community behind it.

factorio

the dedication of the dev is perceptible, almost unlimited replay value and the will release a major extension in 9 days that looks wonderful.

Outer Wilds.

If you like space games and puzzle games (in the sense that you need to piece together the situation you're in), this is a great choice.

Highly recommend not looking anything up before you play.

Subnautica

Hades

I think everyone should play factorio for at least a few hours. It will be some of the most interesting 17 months of their lives.

Crosscode, Disco Elysium, Outer Wilds, Celeste, Fallout: New Vegas

Half life, all of them, in order

Kerbal Space Program

Cyberpunk 2077. I've been known to simp pretty hard for this game, but I do consider it to be one of the best games ever made. The story, the music, the acting, the gameplay, the visuals... Every single part of the game is just masterfully done. I feel it's one of those games that everybody should play; a sort of "milestone" game like Ocarina of Time or Skyrim. Even if you're not a fan of FPS or RPGs, it's worth turning down the difficulty and playing just to experience the best story ever told through a video game, in my opinion.

Terraria

Not everyone likes every genre of game - so here’s my grouped list:

The “I’m a nerd and like to build things and I like to watch lava lamps flow” Factorio

The “I enjoy tough but fair games that I can totally become OP in once I figure it out” Elden Ring

The “I just want to chill” game Stardew Valley

The “I like to build things” game minecraft Honorable mention-Terraria

The “Metroidvania” game Hollow Knight

The “Arpg” game Diablo 2 Honorable mention - PoE

The “I like action and smashing things in an open world” game Neir Automata Honorable mention - God of war (play one of the originals so you can 1st hate the remake, and then get to THAT point, and then happily eat crow and let Kratos be your baby daddy.

I would add Outer Wilds to the list.

You can really only play it once in a lifetime but I think it's the best video game experiences available.

Honorable mention for Tunic and Cocoon for the same reason

A couple of oldies, that deserve to still be played. Disclaimer: I played both games when they were already ~8 years old, and completely outdated in terms of technology.

Planescape: Torment

One of the best RPG ever created, and that is entirely for the world building and writing, and how much of the gameplay ends up being based on these rather than the combat mechanics (which are just ok)

Deus Ex

Again it was way ahead of its time in terms of world building and depth, and it was still an unashamed PC game, that dared to challenge its users a little and didn't need to have a GUI that could be used with a gamepad, unlike the sequels.

I haven't seen it mentioned here, so I'll rep for Noita. It's an amazing rogue-like with great atmosphere and a really compelling world to explore.

There's a chemistry/alchemy system in the game that is really detailed and fun to explore. The game's tagline is "every pixel simulated," and it's not an exaggeration. Noita is like those falling sand games that were popular in the early 2000s, where each particle of sand could interact with other particles. Imagine that, but you're a badass witch flying through the world and blasting motherfuckers who try to get in your way. Your wands can set things on fire or freeze them or melt them with acid or blow them up or other crazy shit.

The wand mechanics are incredibly deep. Like, it's not "turing complete" levels of deep, but the rules for spells interact in incredibly interesting and exploitable ways. The feeling you get when you discover a powerful combo of spells is incredible.

The devs also have a cool policy of turning bugs into gameplay mechanics. I really can't say much about this without spoiling things, so this one is hard to talk about. Basically, if someone finds an exploit, they oftentimes won't "fix" it. Instead, they'll take it and tweak it to add consequences for using the exploit, or they'll balance it a bit to make it harder/remove a bit of the benefit. It's a really cool approach and has lead to a great relationship between the devs and the community. They don't take our toys away, they just make them work better in the world.

I played the game completely blind until I got my first win (it took about 80 hours of playtime), and I'd highly recommend that approach for folks who are willing to tolerate failure and who like to experiment. If it's too frustrating then that's okay, there are a lot of guides out there to help out new players without giving up too much. Many people describe your first win as you beating the tutorial, and there's some truth to that.

It can be gruellingly difficult at times, but it's just so damn good, and there's so damn much of it. I have around 600 hours in in that game which is twice as much as any other game I've played.

Hollowknight my beloved

Valheim

Don't hate me, but I like Cyberpunk 2077. It may have had its problems at launch, and I heard people were promised all kinds of stuff that was not delived, or was delivered only much later, but I never listen to hype anyway. I've played this for many hours. There are great mods for that game that make it even better, and it has such cool characters, such a fascinating world, good music, great design, the combat is fun... I love it.

If I had my way every domicile in human history would have one of these and a pair of decks.

Dishonored!!

I’ll do you one better: completely free.

Check out Ashes: 2063. It started life as a mod for Doom, but is now completely standalone and has more in common with the Metro games than anything else at this point. PC only, but both games and their expansions are 100% free and worth every minute of your time.

If you like good storytelling, worldbuilding, complex flawed characters and/or deep interactive internal monologues, Disco Elysium is unsurpassed.

Valheim is definitely a must buy. It’s a survival game with crafting and building elements.

Chess

There was an outstanding RTS game from 1997 called Total Annihilation. The soundtrack was 11/10, it was made by Jeremy Soule, the guy who did the Skyrim soundtrack. Some might say that Supreme Commander 2 is their most recent successor to TA, but they are wrong. Check out Beyond All Reason (BAR). It's in Alpha and it's free but it's already sooooo good.

There could be hundreds that I post here, but going to just say the ones I go back to again and again.

Satisfactory, The Planet Crafter, Stardew Valley, Death Stranding, Kerbal Space Program, Cities Skyline, Cyberpunk 2077, Stray, Red Dead Redemption 1 & 2, Duke Nukem 3D, Doom 1 & 2, Decent, and of course Skyeim.

Satisfactory. It's so fun automatizing stuff for 4 hours that could have been done manually in 30 minutes. I like looking at all of my work in the game and thinking "how, this is impressive".

If you like building I guess Minecraft is an epic choice. I have sunk hundreds of hours into the game, easily

Mount and Blade Warband for me. Native is fun but the community has made so many total conversion mods for it that can be swapped in and out at the launcher. It can be Game of Thrones, Lord of the Rings, most points of history between now and ancient Rome, and it can even be Star Wars

I agree with the guy that said Outer Wilds, even though I can't finish it because of my thalassophobia.

Personally, the two games that had a really profound effect on me are Disco Elysium and Hi-Fi Rush.

Disco is an incredible political game that really is damn powerful. It's definitely not for people who just want action.

Hi-Fi Rush is a rhythm action game so I wouldn't recommend it to people who hate rhythm games or people who hate action. But it's so fun, so charming and really uplifting.

I only gotta mention one that everyone should play at least once in their lifetime: Legend of Zelda: Breath of the Wild

Skyrim. I know, it's been re-released a dozen times now, it's buggy as fuck, etc etc, but fuck me if it isn't an enjoyable game, even without mods.

Fallout New Vegas. It doesn't treat you like mr savior of the universe, you're a (un)lucky nobody caught in the middle of a power struggle. No essential NPCs, you can kill everyone you come across.

Age of Empires 2. Old as fuck, still enjoyable. Thank god the remaster lets you play with higher screen resolutions.

Katana Zero: Just try it. It's a 2D action platformer with good story.

Celeste. Great fun Mario-level game, but with a deeper story in both game and in development.

Chrono Trigger is a must for anyone that likes RPG's.