Starting some kind of sprite based isometric graphics sim game seems like the kind of thing that would make a fun hobby project but personally, I prefer to spend my time doing hobby operating system development. I won’t be the one to make such a game but I’d make mods for it.

Maybe look into the Flare engine. One might be able to use that for the isometric graphics and clothing layers. If that isn’t quite versatile enough, there’s always Irrlicht or Ogre Engine.