On a recent afternoon, thousands of noncombatants watched from the sidelines as their general ordered his troops across the battlefield and became locked in a fierce duel with the enemy.

At one point, he berated himself for a tactical misstep that could have cost his side the high-stakes conflict. Then he smiled and began outmaneuvering his foe.

¡°I can¡¯t lose,¡± Hikaru Nakamura, 32, said to the exultant onlookers. Victory seemed close as members of the opposing army were vanquished one by one. ¡°I win again ¡ª there you go, guys. Wow.¡±