Factorio, it’s fun from the first minute but you’ll still be learning new things after 1000 hours.

Per my steam library:

Factorio: 3,375.4 hours

Dyson Sphere Program: 2,505.9 h

Stellaris: 2,236.6 h

Terraria 2,629.9h

Skyrim: 1,239.5 h

Dungeon Defenders only has 600 hours on Steam, but I’m well over 2000 hours between Steam and PS3/4

I’ve also got a few thousand hours in Just Cause 2&3, as well as several Gran Turismo games and Forza Motorsport games. Morrowind probably has 2-3000 hours, oh and I’m not allowed near Sid Meier’s Alpha Centauri anymore.

Secret of Mana and Chrono Trigger are probably up there as well since I’ll replay them every decade or so.

BeamNG.

I just can’t stop crashing cars into things in slow motion.

Satisfactory

Oxygen Not Included- very detailed colony sim where scientific things like heat exchange, air pressure, etc. are essential for survival. I swear, my next file will be perfect…

cracktorio

Factorio: 2344

Path of Exile: 2736

Rimworld: 2191

Kerbal Space Program: 1071

I have a bunch of honorable mentions in the several hundred hours ranges that are only not 1k+ because I have severe ADHD and something else became a hyperfocus before they hit that point:

Backpack Hero

Ark

The Last Spell

Timberborn

Factory Town

Dyson Sphere Program

Loop Hero

Brotato

Satisfactory

Path of Achra

Against the Storm

Desynced

Pavlov VR

Sims 3, Skyrim, Fallout 4

Minecraft…

Mine are:

Any Fallout or Elder Scrolls

Diablo 2 or 3

Stardew Valley

Borderlands 2

And I never consider it a real game, but I do sink the most hours in Hearthstone. I’ve been playing it almost daily for the past ten years.

Factorio

The Factory Must Grow

I’m almost 100 hours into my new space age save, and I’ve played nearly 1k hours since I bought it 5ish years ago. By far one of the most enjoyable games I’ve ever played and I highly recommend it to everyone who enjoys sandbox games

Elite Dangerous is my go-to lately.

It’s different to most other games, by not being goal-oriented except for the goals you set for yourself. No main quest line dictating progress. No mandatory tasks. No win condition. Instead, it drops you into a simulation of our entire galaxy roughly 1300 years in the future, where humanity has mastered hyperspace travel and spread through hundreds of star systems.

(To give an idea of the simulation’s scope: Around 85 million systems have been recorded by players so far, and those are a vanishingly small fraction of what’s out there. Space is big.)

I like that it offers a variety of activities to fit whatever mood I might be in on a given day. I can hunt pirates, mine asteroids, engage in a bit of piracy myself, find and collect bio samples, infiltrate rival settlements, venture into vast unexplored areas of space, discover Earth-like worlds that nobody has ever encountered before, defend humanity against hostile forces, photograph beautiful stellar phenomena, rescue stranded survivors, customize and finely tune my ship to perform beyond its original specs, team up with friends, pledge to a political power and expand their influence, or chill out as a space trucker and haul cargo to earn enough money for my next upgrade. It can occupy all my attention, or just be relaxing entertainment while I listen to music or an audiobook.

It’s an MMO in the sense of having a large game world (galaxy) shared by all players in real time, but PvP is optional. One mode exposes you to other players, while another limits you to NPC encounters. You can switch between them at will.

One warning: A space ship has more than a few controls to learn, and they’re better suited to a game controller or HOTAS than a keyboard and mouse. I use button combinations for almost everything beyond basic flight controls, since there aren’t enough buttons on a controller for everything.

The only two games I have that much time in are Factorio and Satisfactory.

I’m amazed nobody has mentioned Kerbal Space Program (first one). That and TF2 are my most played