> I've been looking for a big project to tackle, maybe that's something I can try to start myself :)

I had a similar thought. I was thinking maybe this could even be some web-based system where you could have multiple editors talking to the same engine session, or vice versa.

> Although good UX has been historically the Achilles Heel of open source

Completely agree. Perhaps the best way to go about a project like this would be to establish a few mock use cases up front (i.e. actually try to build a dummy game with your own tools). The magic of UX doesn't appear until you have actually used a thing and start tweaking stuff like animation delays, font sizes, tab order, modal positions, et. al.