It is part of Simon Tatham's puzzle collection, it also has an app on F-Droid:
https://f-droid.org/en/packages/name.boyle.chris.sgtpuzzles/
And the sgt-puzzles package on Debian/Ubuntu, possibly other distros package it too.
It is part of Simon Tatham's puzzle collection, it also has an app on F-Droid:
https://f-droid.org/en/packages/name.boyle.chris.sgtpuzzles/
And the sgt-puzzles package on Debian/Ubuntu, possibly other distros package it too.