Kerbal Space Program.

It won’t necessary make you “smarter”, but it will teach and given you an intuition for orbital mechanics.

I think it’s free this or next week on Epic, and the sequel will be released in about a month or so.

It’s highly moddable, meaning plenty of replayability. As it’s a unity game, it’s written in C#, so if you want to get into modding yourself, it’s very easy too.