I've been wanting a colony/city builder where you gather resources and build up your defenses, as well as the colony/city itself to keep your people fed and happy.
You would get raided by bandits and other factions, and hope your defenses hold up, tower defense style. It would be cool if you could also head down to the battlefield yourself in first person.
As time goes by, you research new technology and evolve your city from ancient to more modern era, which makes you redesign your city to accommodate for the new tech. It would have nice qol so you can copy and paste your paths/roads, walls and fortifications without having to lay down brick for brick - unless you really want to.
Growing into a kingdom/civilization with multiple cities could also be a cool feature, and also open up for invading and taking over other cities to grow your empire. This might also lead to focusing your outer cities on defense, while specialising your inner cities for population and economy growth, as well as research and logistics.
Basically Civilization, Age of Empires, Sim City and more in one neat package.
With family sharing enabled, there's really few of those games that are unavailable anyways tbf.