I was thinking about the usefulness of being able to reboot the engine in a normal application, and I realized that it could potentially be used with downloaded game.darc files as long as they are the same engine version.
One application could be to have a “gameportal” main app which can then download lists of games, and then be able to download each game, and boot in and out of it through using the ability to relaunch Defold’s engine.
Another would be to download mini playable demos of games to promote them. So you could download the demo archive, and then invite the user to play instantly, and then either go to the app’s store link, or return back to the main game. Of course you can bundle demos like this in with your main game as their own collections, but being able to stream them in remotely and arbitrarily would be nice - they just have to be built with same engine version, and be made to know how to reboot back into the main project.
I don’t think this is currently possible to do (am I wrong?), but it should be possible with some changes to allow it.