Main difference with anki is that anki explicitly discourages trying to make dependencies between flashcards or decks. I tried to work out something like that into Anki, but as I saw it, dependencies were core to what I had in mind. There's some similar functionality in supermemo, but it's based on a tree, not a graph, so it was inherently limited.

No experience in mobile at all so that'll have to wait, but a GUI/website/app that works on most platforms is something I would like to work out eventually.