

I used to always use Minecrat for this. Sure, they can’t do everything immediately, but I put the game on peaceful and let them explore at their own pace.
I say “used to” because Luanti (formerly MineTest, an open source Minecraft Clone*) is finished and free.
(Okay, Luanti is a lot more than a Minecraft clone. But for this discussion that’s all one needs to know.)
Vibrant ecologies have diversity. Fully unified government isnt diverse, and would be bad for at least some people. I hope all of our governments suck less, but still have each-other to compete with.