Asklemmy

Factorio. The factory must grow. Started on my Switch until I could no longer save games, then migrated to laptop. Because the Factory. Must. Grow.

Never in my life have I been so hooked on a game.

Cyberpunk. They fixed most of the issues the game had at launch. There's a dlc coming out soon too that will add a bunch of hours, and with it they are reworking loads of mechanics for free. Can't recommend it enough.

I've reeeaaaally gotten into the rogue-like/lite genre. Dead Cells, Hades, Slay the Spire, FTL, Vampire Survivors... Just endlessly fun and entertaining. Also for all you Vampires lovers, I just picked up a game called Halls of Torment during the Steam sale for cheap. Super fun "vampires-like"

Dwarf Fortress is beautiful.

Rimworld

Rimworld.

It's kind of funny because I bounced off the game hard the first two times I played it. What really did it for me was the Ideology DLC, gave it a shot on a whim and the amount of structure it gave me for RPing colonies was exactly what I was missing.

Hundreds upon hundreds of hours in now, and it is the game I keep coming back to. Not to mention one of the biggest modding communities I have ever seen in a video game. The only video game subscriptions I maintain currently are to a few Rimworld modders whose work I really enjoy. When I am not playing it, I am working on ideas of themed mod packs to put into it.

Dyson Sphere Program is a close second, it's my favourite factory-builder. It is still in early access but is a VERY polished experience already. Amazing dev communication too.

Slay the spire. Probably have close to 1000 hours playing it and I'm still addicted.

Witcher 3 wild hunt. Game was released in 2015 and we are still getting regular patches 8 years later. Patch 4.03 was just released last May. Engaging storytelling, a vast open world along with 2 expansion pack, deep role-playing elements to create a memorable and immersive gaming experience.

Rimworld - 2000 hours so far. I'm not done yet. The mod community and periodic dlc keep it alive for me.

RimWorld.

Yes, I am a degenerate.

Dwarf Fortress, been playing it off and on for many years now. I happily bought the steam version when it came out!

FTL. Theme song triggers ptsd in my wife.

Binding of Isaac

There's no game I don't eventually get tired of, but here are three that are fantastic and I can recommend playing for hours and hours:

• FTL
• Slay the Spire
• Darkest Dungeon

All indie titles, none of them new, still fantastic and well worth it if you haven't played any on this list. Also all challenging roguelikes, so be warned. =P

Vampire Survivors on the steam deck.

The Outer Wilds. Best space exploration game with environmental storytelling I have ever played. And that ending...chef's kiss made me cry.

Cyberpunk2077 at the moment. Got more than 250 hours on it. Before that I played Dishonored a lot and that before the very first Deus Ex. The story was just incredible and IMHO still is one of the best in video game history.

Mindustry. People compare it to Factorio, but Mindustry (which also has an Android version) is open source.

Kerbal Space Program

On my 3rd playthrough of Fallout: New Vegas

The most recent, Dave the diver!!

Roller Coaster Tycoon.

Please don't make fun of me but I am a die-hard SimCity guy

Kenshi. It's very unique and one of my favourite games. It also has an amazing modding community.

I haven't see Horizon Zero Dawn in the comments so far. This is probably the best (by graphics, game play, characters, story lines) game I've ever played. I really hope that Horizon Forbidden West is released for PC soon.

Cities Skylines for me. It's like building my own little world that I would want to live and work in

Factorio

For a hot month at a time, The Sims, then never again for the rest of the year

RimWorld, I can't stop playing it for at least 6 hours every time I launch it.

Also Factorio until I got stuck on making the fucking trains work

Age of Empires 2 in campaign mode

Factorio, Satisfactory, and Minecraft. Generally sandbox games keep me interested the longest since you're just limited by your creativity there.

Portal 2

I got Slay the Spire recently from the steam summer sale since it’s so cheap. I haven’t been able to put it down. It’s such a time suck, and I normally don’t even like card games. I would 100% recommend it.

Skyrim, Fallout 4 and Might & Magic VIII

The Mass Effect trilogy.

Kenshi

I'm flabbergasted we're getting no metroidvania love in here so I'll list my two favorites: Hollow Knight and Blasphemous. Both with sequels coming out this year which I'm so excited about!

Looking at my steam:

Total: Factorio. Though I do think I need to put that one on hold after I'm finally done with my current save - which is not far out anymore. Also, this game has multiplayer so it may technically not count.

Recent: Derail Valley, a very down-to-basics train simulator, focusing on cargo rail in a fictional rendition of an area in the Balkans. They recently put out a major update, which makes all kinds of simulation features much more expansive.

Deep Rock

Minesweeper.

The Binding of Isaac. It is too addictive

STALKER - with mods this game looks amazing and it's so immersive. I had so many fun/terrifying hours on this

Bayonetta

Dwarf Fortress

Cyberpunk

Mass Effect

Morrowind

Inscryption

OpenTTD.

Rollercoaster Tycoon / OpenRCT2

Transport Tycoon Deluxe / OpenTTD

While they do now have multiplayer modes thanks to their corresponding open source projects, I still think the spirit of these games is firmly in the single player pc game category. Best of all they're both free and available on any OS!

Civilization for me... I don't mind the newer versions but I'm old enough that I've played it since Civ I and I do sort of feel like it's lost something as the graphics have improved and animations were introduced. Still, irrespective of the version, every game is a little different and eats hours like nothing else.