I called it a sim because there's management in the game and more restrictions than in the typical sandbox game I've played. **I'm also separating sandbox from open world.
That's true, and tiny tower also had a sort of leveling mechanic where you add new floors to your tower. Tiny tower is certainly a freemium game, but it feels much more elegant. I guess that's the ultimate problem with energy and leveling mechanics, they feel like nothing more than cheap compulsion systems that are just tacked on to bring in more money. I don't know much about this game in particular, so I can't give specific advice, but I would encourage you to find a more organic way to introduce these elements into your game.
I know some people don't seem to like freemium but as long as it does not interfere to much with the actual gameplay then I'm fine with it.
