I'm working now for some time with C2 and I like it very much!
Working on larger projects I had some ideas for enhancements with the gui and maybe you are interested implementing it...
-> working with sprites (copy & paste) the layers are very useful to group different types of elements.
It would be nice (optional) to paste sprites on the same layer the copied sprite comes from (unattached the actual selected layer)
Even when selected & copied several sprites from several layers (each should pasted to the depending source(copiesource) layer.
(e.g. wall-sprite copied from layer1 but current layer is layer4. when paste the wallsprite is placed in layer1)
-> zooming (with ctrl+mouse wheel): it would be nice, if the zooming center would be the mouse position (known from Adobe PS).