Overlapping Unity Players w/ Transparency

That would be cool, but why would you do that rather than building everything into one unity build? (Not criticizing you for trying, just wondering what the use case is ...)

I knew someone would ask haha, it's a totally valid question. The benefit to this decoupled approach is that foo and bar can now be updated and released independent of each other. Also using this example, say I wanted 5 different variants of bar.unity3d (rain, snow, hail, etc.). Now I don't have to put all of that into foo.unity3d.

This is all to get around unity's inability to bundle c# script code into asset bundles. Otherwise I could have foo come up and load remotely whichever bar asset bundle I wanted and run the associated scripts for that scene. I understand from Unity's point of view that this is a security measure.

I should just note (for more context) incase you think that this is a weird thing to achieve, I am one of the few evaluating Unity for non-gaming applications.