This was an entry in the GBAX 2005 Coding Competition, the download link from there no longer works. It's listed in temp's download section but that just links to filetrip (R.I.P.), and I can't locate a working download via google. I did gather that there were multiple version releases, but the competition entry appears to be the newest and biggest file, so likely most complete (this random page lists it with filename "Picross Advance by Phantom (GBAX2005 Entry) (PD).gba", 648,60Kb - tho no download link). It doesn't show up on the usual gba homebrew index sites, IDK if it got scrubbed from existence because of a copyright claim or something, or something else weird happened.
It's not life or death or anything, I just like picross, and now that I've seen this existed I find its absence mysterious.
It's not life or death or anything, I just like picross, and now that I've seen this existed I find its absence mysterious.