I am currently working on a new version of Lost in Marble Gardens. The levels will contain new puzzles that were not in V4.0. This will be a harder version of the previous one. I don't know whether to call it V5.0 or something different.

Yes, I am also still working on Crystal Cave. About 70-75% done I think. I might remake it in the new Crysillis shortly after that's done.