Why I made it
I want my computer to reach a much bigger library than the one on its disk. The example that started it: I play old games in emulators, the collections already exist, and other people have already sorted them. I should be able to add a link and have all of it ready to use, without downloading and reorganising everything myself.
Interplanetary Drive makes a collection part of your file system. Files fetch when you open them. Pin the ones you care about and they stay on your disk. Your applications see ordinary files, so nothing has to learn a new library format. Games are the first case; music, video and photo collections are the same problem.