Next month marks ten years since the owner of the Sudocue.net site, Ruud van der Werf, disappeared from the sudoku scene into the ether without any warning whatsoever. Apparently he moved on to other interests. (We have it on good authority that he was alive and well at least six months after his disappearance.)
I am grateful that at least the Sudocue.net site is still up and the puzzles and software are still available, even though no new puzzles or software versions are being generated. It also appears that perhaps Ruud returned at some point (or authorized someone to do so on his behalf) during 2016 to update some links (especially to the software and puzzle collections formerly stored on the sudokuvault site).
Ruud, a very heartfelt thank you for your contributions to the sudoku world. I hope you continue to be well and happy in whatever endeavors you are now pursuing. If you are reading this and would consider allowing someone else to take ownership of the Sudocue.net site so that it can be continued into perpetuity, I would like to recommend Jason Linhart of enjoysudoku.com (and site owner of this forum). I believe he has the knowledge, resources, time, and respect for your work to do it justice.