This week we enter the complex world of the back game. As a reminder, the definition of a back game is one where one player holds two or more points in his opponent’s board.
The objective of the person playing the back game is to hold both the points in his opponent’s board whilst using his remaining checkers to build a strong home board. If the back game is well timed his opponent will be forced into leaving a blot, probably exposed to a double shot. The player of the back game then (hopefully) hits the shot and contains the hit checker.
As the player of the back game will normally own the doubling cube the final stage is to win the game with a well-timed redouble.
The first piece of advice about back games is this – avoid them unless absolutely necessary. They are great when they work but they are difficult to play and when they go wrong you quite often lose a gammon. No matter how well you play one bad roll can destroy even the best timed back game. Look at the position above and see what would have happened if black had rolled double 4 – his beautiful home board would have been ruined forever.
However, black has a 51 to play and must choose between (a) 23/18, 8/7 and (b) 8/2 (I hope no-one considered playing 21/15??). Which shall it be?
The game has reached its climax and the next two rolls (one by each player) could be decisive. (a) guarantees black’s timing by freeing the spare man from the rearmost point whilst (b) makes a strong home board but risks some bad numbers (such as 44 and having to run off the 21-pt with any 6) next turn. Are we any clearer?
Having looked at the general considerations what about specifics? If black plays (a) then nearly all of white’s 1’s play much better than after (b). The second consideration is that after (a) and a subsequent hit by black, black’s home board will not be as strong as after (a) and white may be able to return hit from the bar.
These specific considerations outweigh the generalities (often the case in late game positions) and (b) is correct as can be seen from the rollout below. In the game black chose (a) and white responded with 41, played 8/7*/3. Black fanned, white never left a shot in the bear-off and easily won a gammon.