Anomaly, kenshi.

I think I’d say Minecraft since I’ve probably put tens of thousands of hours into it since 2011

I don’t fully understand what you mean by “it’s all in the gameplay game” but based off the fact you included a picture of one of the original rollercoaster tycoon games, gonna have to say rollercoaster tycoon 3.

This (sandbox games that are all about “pure” gameplay, where the narrative is made by the pseudo-random events) is my bag!

In no particular order except for #1, these are my top-10:

1. Kenshi Post-apocalyptic alien planet sandbox that can be a colony simulator, a faction-combat game, an exploration and boss-fighting game, and so much more. This is by far and away my TOP recommendation.
2. Rimworld Dwarf Fortress-like colony simulator set on proc-gen alien planets. Supremely mod-able.
3. Starsector Sandbox space game with a bit of everything. You can play it in so many ways, and there are so many encounters and missions and things to do. Tons of mods.
4. Mount and Blade: Warband A medieval-combat “simulator” where you lead a… Warband of soldiers around a faux medieval world. First-person combat with a lot of great complexity. Supports mods.
5. Derail Valley A train-driving simulator, where you just take contracts to haul stuff between towns/stations/etc. Multiple engines to drive, and a lot of cool physics to contend with.
6. Project Zomboid Zombie apocalypse survival simulator, with multiplayer. Lots of mods.
7. Spore A sandbox classic, where you usher a species as it evolves from protozoa to being an interstellar species.
8. The Sims 3 Playing house for adults (and kids). Build a house, decorate it, get a good job, have kids and pets. The unattainable Millennial fantasy.
9. Starbound Universe exploration sandbox, with a bunch of humanoid aliens you have to ally with to defeat a big monster thing. Moddable.
10. X4: Foundations Economic simulation sandbox set in space. Build stations, ships, influence wars between empires using economic sway… Very very slow, but fulfilling.

Cataclysm: Dark Days Ahead. It’s the Dwarf Fortress of zombie survival games.