I'm no great shakes at backgammon, so this program suited me fine - it played a serious game, didn't get impatient, and never made rude remarks about my skill.
The screen display is uncluttered and easy to use, with the dice simulated at the bottom of the screen.
To move you just type in the letter corresponding to the position you want to go to - the computer does the rest. Illegal moves are refused, with reasons. There's also a "doubling cube" facility for those who like to gamble.
Four levels are offered, and on the simplest, the ZX81 occasionally made a move which even I thought a bit silly. The other levels take longer, but on each you have the choice of fast or slow modes.