My last one of this ilk is still around and still running. It too was written in assembly language, but for a color-but-text-mode-only DOS dog. Oddly enough, my wife still plays this one occasionally on our POS machine at the store (which is an old PC/XT).
This cryptograms program includes 199 puzzles and as many frills as I could think of that would adapt to the fun world of Just BASIC. I've received scant feedback on my last contribution, but I'm hoping at least a few will enjoy this one. My granddaughter gave it two-thumbs-up, by the way.