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.