Games

I liked ksp2

If you're saying that you liked the (unfinished, abandoned, poorly-rated) Kerbal Space Program 2, you might play the original, which is better-regarded.

On the "factory" side, maybe some colony simulators? Someone else mentioned Rimworld. That's got a bit of DLC, but I think that even the base game has pretty good value for money. Oxygen Not Included is another colony sim that focuses more on the building/automation/physics side; I think that you'll get a lot of hours out of that.

Dwarf Fortress is another colony sim, has a freely-available classic version or a commercial graphical build on Steam. Steep learning curve, but lots of mechanics to explore.

I like Cataclysm: Dark Days Ahead, though it has a pretty punishing learning curve. Open-world roguelike. It touches on both the RPG (well, not much by way of plot, but in terms of building a character) and the factory (build buildings, faction camps with NPCs, and vehicles) side. You aren't going to run out of gameplay complexity to explore any time soon on that. Open source and freely-available, though there's also a commercial build on Steam.

I have not played Elin, the successor to Elona, but it might be worth a look too if you are looking for a game with both a sandbox aspect and RPG aspect.