There's pretty much only one 4th-dimensional game I know of:
Miegakure, developed by Marc ten Bosch in a custom engine. I don't know of anything like a widely available editor for that sort of thing, but wrt your question about how hard it would be to develop a 4D game, the answer is
extremely. Miegakure
still isn't out despite being in development for about a bazillion years.
3D is a different matter--there are
quite a few editors for making 3D games these days! Unity and Unreal Engine are the two most widely used, with the open-source Godot engine gradually gaining in popularity. Each engine has points in its favor; personally, I'm using Unity these days.
(P.S. I edited out the advertisement in your post. No more of that, please, or I'll have to remove your account.)
