The following positions address checker play in unlimited games. An unlimited game means a game that stands alone, where match score does not affect the decision. Tap the play you would make at the board.
The candidate plays are ranked by equity, the value of one play measured against the alternatives. Beside each play you will see W, GW and GL: Blue’s chances to win the game, to win a gammon, and to lose a gammon. Delta is the equity a play gives up against the best play. On every card, each candidate play was rolled out 1,296 times to ensure accuracy.
The best play earns a green BEST badge. A play that gives up a little equity is an ERROR; one that gives up a lot is a BLUNDER. Have fun.
Blue is priming, because the way to beat a well-timed back game is a wall in front of the anchors, not a race. White holds a 1-3 back game with five checkers on Blue’s 1 and 3 points and trails by only 14 pips, so White has plenty of time and the game will be long. Blue plays 13/9 11/9, making the 9 point to hold the 5, 6, 8 and 9 points, with the 4 and 7 points as the next targets. The checker left on the 11 point can be hit by only 3 rolls, and the straggler on the 24 point costs Blue a single pip if it is hit. The safe 24/20 13/11 leaves no blots but builds nothing: it piles a third checker on the 20 and 11 points while five White checkers wait behind only three blocking points. It loses 0.184 equity, a BLUNDER.
Blue is priming, and with six White checkers back and an 83-pip lead the danger is not being hit; it is running out of moves before White does. White holds Blue’s 1 and 3 points with three checkers each and still has nine checkers to play with. Blue plays 11/7 8/7, making the bar point for a four-point prime from the 4 point to the 7 point. The blots on the 8 and 11 points face 15 shots between them, and the checker on the 2 point can be hit by any 1, but White’s board has only two points, so a hit simply sends a Blue checker around for more timing. The quiet 13/8 covers the 8 point and makes nothing new, leaving six White checkers behind three blocking points. It loses 0.169 equity, a BLUNDER.
Blue is priming, and the 5 point is the blocking point that matters most against a 1-3 back game. White has five checkers on Blue’s 1 and 3 points, trails by 60 pips and has a loose checker on Blue’s 15 point. Blue plays 8/5 6/5, making the 5 point and holding the 4, 5, 6 and 7 points as a four-point prime. The blots left on the 8 and 11 points face 15 shots, and a hit costs Blue little against a White board of only two points. Hitting with 18/15* 6/5 sends a sixth White checker back, hands White 15 pips of extra timing and leaves a Blue blot on the 5 point facing 22 return shots from the bar and the anchors; a checker on the bar is a checker that never has to break White’s front position. It loses 0.265 equity, a BLUNDER.
Blue is priming, and the plan is to make the 4 and 5 points in front of the anchors rather than to pick a fight. White holds Blue’s 1 and 3 points, has a loose checker on Blue’s 4 point and trails by 49 pips, so five back checkers are a burden. The 5 must enter, bar/20, and Blue plays the 4 with 13/9, bringing a fourth builder to bear on the 4 and 5 points; the blot on the 9 point faces 25 shots, but a hit costs Blue only 16 pips from a big lead and gives Blue more time. Hitting with bar/20 8/4* costs White just 4 pips, strips the 8 point and leaves blots on the 4 and 8 points facing 20 shots, and the hit checker comes straight back in on the 1, 3, 4 or 5 points. It loses 0.029 equity, an ERROR.
Blue is priming and already has the full prime: six points from the 4 point to the 9 point, with five White checkers trapped behind it and White holding the cube at 2 in the hope of a late shot. White can only wait, so Blue’s job is to bring the last outside checker home without leaving a shot and keep the prime whole until it has to break. Blue plays 13/6, bringing the midpoint checker in with no blot anywhere. Breaking the 8 point with 8/2 8/7 clears in the wrong order: it hands White’s checkers a landing spot on the 8 point while the midpoint checker is still out, and the spare dropped on the 2 point is buried where it will never help clear another point. It loses 0.107 equity, a BLUNDER.
Blue is bearing in against a 1-3 back game, and the rule is to clear from the back, one point at a time, leaving no gaps. Blue holds a full six-point prime from the 4 point to the 9 point and leads by 71 pips; White’s four back checkers can only wait for a blot. Blue plays 9/5 9/6, clearing the 9 point cleanly and leaving a five-point prime from the 4 point to the 8 point with spares on the 5 and 6 points. Clearing the 8 point first with 8/4 8/5 is just as safe this turn, but it leaves the 9 point stranded behind a gap: those two checkers must later jump the empty 8 point, and White gains a landing spot right in front of the anchors. It loses 0.058 equity, an ERROR.
Blue is bearing in, and the job is to clear the outside points in order, keeping spares on the points still to be cleared and burying nothing. Blue leads by 95 pips, so there is no hurry; White’s five checkers on the 1 and 3 points simply wait for a shot. Blue plays 8/4 8/5, clearing the 8 point with both checkers together and keeping three checkers on the bar point with spares on the 5 and 4 points for the next clearance. Keeping the 8 point with 7/4 6/2 leaves no blot either, but it strips the 7 and 6 points to two checkers each and buries a checker on the 2 point where it does nothing; the next roll must then clear a stripped point. It loses 0.049 equity, an ERROR.
Blue is bearing in against a 1-3 back game with an 88-pip lead, and the order of clearing matters more than the race. Blue has two outside points left, the 7 and 8 points with two checkers each, and White’s four back checkers wait on the 1 and 3 points for a blot. Blue plays 7/4 7/6, clearing the bar point first because it is the harder point to clear: a blot there is hit by every 4 and 6, 20 shots, while a blot on the 8 point faces only 11. The two checkers on the 8 point then come home with any 2, 3, 4 or 6. Clearing the 8 point first with 8/5 8/7 piles four checkers on the bar point, the point that is hardest to clear, and Blue must still break it later facing the same 20 shots. It loses 0.104 equity, a BLUNDER.
Blue is bearing in with a 101-pip lead against a 1-3 back game; the race is over, and the only question is whether Blue can clear the bar point and the 6 point without leaving a shot. Blue plays 7/5 6/4, taking a spare off the bar point and a spare off the 6 point to fill the 5 and 4 points, leaving two checkers on the bar point, three on the 6 point and four each on the 5 and 4 points with nothing buried and no gap. Breaking the bar point with 7/4 7/6 leaves a lone checker there facing every 4 and 6, 20 shots, when there was no need to leave anything, and White’s four back checkers would be delighted. It loses 0.157 equity, a BLUNDER.
Blue is bearing in against a 1-3 back game with White holding the cube at 4 and a four-point board waiting for any Blue checker that is hit, so every shot matters. Blue leads by 44 pips and has two points left to clear, the 7 and 8 points. Blue plays 7/4 7/5, clearing the bar point first because it is the harder of the two: a blot there is hit by every 4 and 6, while a blot left on the 8 point faces 11 shots. The two checkers remaining on the 8 point come home with any 2, 3, 4 or 6. Clearing the 8 point first with 8/5 8/6 leaves the bar point to be cleared last, when the spares are gone and more rolls force a blot there. It loses 0.050 equity, an ERROR.