Ego has claims to be one of the strongest Go-playing programs available, though I have found it to be considerably weaker than HandTalk. However any Go-player stronger than 10-kyu should be able to beat any program that currently exists, Ego and HandTalk included; so unless you are in the range 10-kyu to 15-kyu it is likely that appearance and ease of use may matter more to you than absolute playing strength of a program. It plays fairly fast, taking typically two seconds but up to twenty seconds per move (on a 66MHz 486DX). It uses only Japanese rules.
As it plays, it continuously gives its assessment of the amount by which it is winning or losing. If you don't want to see this, you can switch it to showing its assessment of how much territory each side has, or if you don't want to cheat, to the numbers of prisoners (click on the place where this information is shown). You can also switch on or off the "safety" option, which causes it to show the "alive"-ness of every group and where the secure territory is.
Should you get bored of playing against it yourself, you can even run two copies of Ego at once (if you are using the Windows operating system), and play one personality against another, copying the moves from one board to the other yourself. I found a game between Earthy (territory) and Airy (influence) interesting. Earthy started by making secure corner territory, while Airy made thickness which was often pointing in the wrong direction. Then Earthy lightly annulled most of this thickness. Finally Airy demonstrated that its influence was not nearly as useless as I had been assuming, by creating territory in unexpected places and winning the game. Most instructive.
A couple of apparent defects are easily remedied. First: you may find, if you are incompetent in the use of your mouse, that a lot of stones suddenly disappear in the course of a game. This is recoverable. What you have done is double-click on a stone, and it has reverted to the point in the game at which that stone was played. You can recover by using the "Final" button, which takes you back to the end of the game as so far played. The second defect is more mysterious, and the author has acknowledged it (it's always an encouraging sign when the author of a program admits the existence of a bug). When the program plays a stone, it usually flashes it so you can see where it has played. But sometimes it fails to do this. You can then force it to flash it by saving the position (just click on the "Save" button).
If you want to get an impression of what Ego is like before paying for it, there is a free cut-down version of it available, called EZ-Go. This has all the features of Ego, except that only two of the nine personalities are included: Psycho and Leaper. Psycho is the stronger of these, but it does not approach the strength of Samurai.
review by Nick Wedd, July 1995