Why you can’t always choose which die to play first

Players sometimes write to us about a move that CUBE Backgammon won’t allow and ask whether the game is broken. They have a checker on the bar, an open point and the right die to enter there, so the refusal is puzzling.

In the example below, the app is working as it should: backgammon requires you to use both dice whenever there is a way to do so. You cannot choose an order that uses only one when another order lets you play both.

Try entering with the one

You play Ivory, toward point 1. A one brings the checker from the bar to point 24, which is open. The entry itself has no problem; the difficulty is finding somewhere to use the six afterwards.

From 24, a six would land on 18, where Red has two checkers. The ivory checker on 8 cannot use it either, because point 2 is also closed. Your other checkers are on points 3, 4 and 5. None can move six points, and you cannot bear them off while you still have checkers outside your home board, points 1 to 6.

That order would leave the six unused.

Now enter with the six

The six brings your checker from the bar to point 19. You can then use the one to move a different checker, from 8 to 7. Both dice have been played, so this is a complete legal turn.

The checker that enters does not have to use the second die. That is easy to overlook when your attention is on getting it off the bar.

Because this second order is possible, the first is not an alternative you may choose. In CUBE Backgammon, the move controls keep your first move on a path that can complete a legal turn, which is why the open entry on 24 is unavailable here.

What if you really can play only one die?

Sometimes neither order allows both dice. If you can play only one number, you must use it. If either number can be played on its own but there is no way to use both, you must play the larger one.

This is a separate rule from the example above. There, both dice can be used, so the question is how to use both. Only when that is impossible does the larger-die rule decide between two single-die plays.

Doubles follow the same idea: you get four moves of the same number and must use as many as are legally possible. You cannot stop early to keep a point closed. That obligation is part of why waiting for a chance can be difficult, even with a position you would happily leave untouched.

When both orders are legal, the choice can still matter

Two legal orders may finish with your checker on the same point while hitting different checkers along the way. The distance is the same, but the position you leave your opponent is not.

Our example of a move that changes with the match score uses exactly that choice. Both orders of a 6–1 are legal there, and only one hits.

If an entry or move seems to be missing during your next game, look at the dice still to play. Try the other order, then check whether another checker can use the remaining number.