Samesby

It all began the day two young otters, Brook and Ripple, decided they wanted to race each other. Each of them grabbed a random board off the pile, they counted down together, and off they went, playing as fast as their paws could fly. Ripple finished first by a wide margin and leapt up whooping.

"I win! I win!" Ripple shouted, doing a little victory spin.

Brook was frowning. "That's not fair," Brook said. "Your board had one enormous empty patch that opened up half the board in a single click. Mine was stuffed full of tricky numbers all the way across. You got an easy one."

Ripple's whoop trailed off. "I didn't pick an easy one on purpose," Ripple said, and a moment ago the win had felt wonderful, but now it suddenly felt a little hollow, like biting into a cake and finding it was mostly air.

Samesby came waddling over, beaming as brightly as ever. "Nobody did anything wrong," he said at once. "Nobody cheated, nobody meant to be unfair. But Brook is right that it wasn't a fair race. You were racing two completely different boards, so the result can't tell us who played better. Maybe Ripple was the faster player. Or maybe Ripple simply got a luckier board. From this race, there's no way to know which. The board and the player are all tangled up."

He held his two identical boards up side by side. "Let's do it properly this time. I'll make you a race code."

He tapped out a short code of letters and numbers. "When you both type in this code, the League builds the exact same board for each of you. The same mines, in the same places. The same numbers. Even the same free opening at the start. Square for square, identical in every way. Brook, you'll play one copy. Ripple, you'll play the other."

The otters typed in the code, and two identical boards appeared before them.

"Now," said Samesby, "whatever happens next, it's entirely about how you play. Neither of you can end up with a luckier board, because there's only one board. It just happens to be in two places at once. The luck is the same for both of you, so it can't tip the race."

They counted down together and began. This time the race was close, genuinely close. Brook, who had been so frustrated before, spotted a clever two-number proof near the middle of the board and pulled ahead. Ripple fought back with a well-placed chord that opened a whole ring of squares at once. They finished within a few seconds of each other, with Brook just barely in front.

Brook grinned from ear to ear. Ripple laughed out loud. "You got me," Ripple said, "and that one really counts. Same board, fair and square."

"And here's the very best part," said Samesby, clapping his flippers together. "Because it was the same board, you can compare much more than who finished first. You can compare how many clicks you each used, and your efficiency too. Maybe Brook was quicker, but Ripple wasted fewer clicks. On different boards, those numbers wouldn't mean much side by side. On the same board, every one of them means something. You might each discover you're better at a different part of the game."

The otters compared their scores. Brook had been faster. Ripple had been more efficient, with fewer wasted clicks. Each of them had won something real.