Alliance Correspondence: Battle Swayers bears the Japanese title 決戦前の書状 ("Letter Before the Battle"), and by sending letters, you can invite or prevent betrayal to affect the course of battle.
Players are divided into eastern and western armies and aim to win the battle at Sekigahara, a strategic location where the Tokaido and Hokkoku side roads intersect. Each turn, you take three of the six rolled dice, then use their numbers to check your faction sheet and arrange the military commanders.
The game ends when a certain number of military commanders have lined up in their formations, and you earn victory points by comparing the strength values of each area, but you must also send letters in advance and be on the lookout for betrayal by your friends and enemies that can reverse an outcome you thought was certain.