They were written by Bruce Wilcox, but he is no longer associated with them. They are now supplied by Nemesis Enterprises, a company controlled by his ex-wife, Leslie Bianchi. I have tested only the Windows version, but I have no reason to think that the other versions are much different. It is primarily a Go-playing program, but has a number of features which add to its value for Go teaching.
Installation is easy.
It uses Japanese scoring and handicap stone placements. I found is easy to beat. Once it knows it has lost, it offers to resign. If you play on to the end of the game, it calculates the score. Perhaps more valuable than its playing strength are the evaluations of the position which you can ask it to make.