Path of Exile. Hands down.
I just broke 1400 hours and still going strong. There’s so much to do and so much to learn, and it’s so good at rewarding grinding and keeping you chasing those incremental improvements. It’s 100% replaced RuneScape for me.
I have broken 1000 hours with Cookie Clicker, Guild Wars 2, RuneScape, and Eve Online. I don’t recommend the latter two anymore, but CC and GW2 still hold up.
Honorable mention to Factorio. I’m still in the hundreds but it’s climbing.
I, too, will still be playing Factorio.
Ooh. I’ve heard of Frostpunk and Tropico but never played them myself. If they’re similar to Rimworld I need to check them out.
Rimworld is a great Colony Sim if you love the idea of Dwarf Fortress but want a gameplay experience that’s much more accessible with a much softer learning curve.
It plays into the chaotic post apocalyptic Mad Max style hellscape fantasy really well, and does not attempt to police your morality. You can love and care for your colonists, meeting their needs and growing to know them as individual people with their own unique stories, or you can play as efficiently or sadistically as you like, throwing ethics out the window and following the Geneva Suggestions wherever you deem prudent.
The base game is good for hundreds of hours of play, and expansions bump that up to thousands of hours of fun, but it also has a very healthy modding community if that’s still not enough.
If you’re unfamiliar with the Colony Sim genre, the basic idea is that you start with a set of semi-randomized colonists on a randomized map and need to build up a functioning Colony to survive. You the player take the role of a manager or overlord and set tasks for your colonists to complete, which they then take time to carry out while you watch and plan the next set of tasks. You need to gather materials, build shelter, grow or hunt food, defend yourself from wildlife and raiders, and recruit new colonists.
Rimworld in particular has fun building mechanics with an emphasis on building power grids and heat management (air conditioning and heating to keep your colonists comfy and keep food from spoiling). It’s a lot like a top-down Oxygen Not Included, but with simpler mechanics and more focus on its (procedurally generated) story.
Oh, hey! Another Ratchet: Deadlocked fan in the wild!
No wait…
Void Stranger is a relatively recent one. It’s a Sokoban style puzzle game with layers of puzzles and a ton of hidden depth.
It took me 50 hours to feel like I beat the base game and I haven’t even touched the post-game content they added after release. I have a folder full of text files with notes and clues and puzzle attempts and one of the best puzzles involved taking several screenshots and stitching them together in an image editor.
La Mulana is another one to check out. It’s a metroidvania heavy on puzzles and exploration that’s actively hostile toward the player. It’s an exercise in frustration and every inch of progress is measured in blood. Every bit of information is important, and there’s a lot of information to untangle. I haven’t come close to beating it yet and my notes from just the first few floors are extensive.