By way of an update... I ditched what I created in the first two weeks. It simply wasn't practical and was suffering from poor performance due to how I'd implemented the rendering and image storage.

I now have a texture atlas component that you can just add images to and then have it create large (16384 x something) texture images which should reduce the number of texture binds and also allow me to do some more optimisation. At the moment, I'm starting to design the structure of the project data and some of the scripts etc.

If you fancy popping along to a stream, I'm happy to field questions etc.