When it comes to "Fraymakers"? It has a great basic idea, but...here's what I think it should have, as far as mechanics, go.

= Items (Consumables & throwables, at least. That way, it would make the use of 2D game sprites easier.)
= Custom bossfight design support
= Having the "Fraytools" built INTO the game, itself. (Complete with the official plugins!)

And...that's basically it; I don't know what else to suggest, really.