Age of War is a fast-playing game of conquest. Fourteen cards are laid out at the beginning of the game, each showing one castle and the symbols required to conquer this castle, with the symbols separated into battle lines. Each castle belongs to a clan, some clans have only a single castle and some have up to four.
A player begins his turn by rolling seven dice, the six sides of which show archery, cavalry, daimyo, and 1-3 infantry. He then chooses a card and uses the symbols rolled to conquer exactly one of the battle lines on this card (by placing the appropriate dice on that line). If he can do this, he then rolls the remaining dice, hopefully conquering another line; if he can't conquer a line, he removes one die from play, then rolls again. His turn ends when either he conquers every line on the card (in which case he claims it) or he no longer has dice left to roll.
Each card is worth a number of points. You can conquer cards owned by other players, but you are require to conquer an additional daimyo line in the process. If a player owns all the castles of one clan, however, those castles are secure and can't be taken. Additionally, these castles are now worth more points because you've united the clan under one ruler (you) and strengthened your hold.
When the last card is claimed, players add up their points, and whoever has the highest score wins.