| The NES manual calls Nobunaga's Ambition a bestseller in Japan for over five years and says the American version was improved many times before it arrived. | p. 6 (PDF p. 5), Introduction | Manual |
| Both scenarios start in spring 1560. One covers the 17 fiefs of central Japan, and the other all 50 fiefs of Japan; the goal is to unify them. | p. 10 (PDF p. 7), Scenario Selection | Manual |
| One to eight people can play, each answering the setup questions in turn. | p. 11 (PDF p. 7), Selecting Number of Players | Manual |
| A turn is one season, four to a year, and each fief the player rules gives one order per season, so a player with more fiefs gets more orders. | p. 11 (PDF p. 7), Displays, Main Display | Manual |
| The NES main display offers 21 commands, Move, War, Tax, Send, Dam, Pact, Grow, Marry, Trade, Hire, Train, View, Build, Give, Bribe, Assign, Rest, Map, Grant, Other, and Pass; each fief's one order a season is chosen from them. | p. 18 (PDF p. 11), Main Display Commandspp. 19–23 (PDF pp. 11–13), Command 1 to Command 21 | Manual |
| Some actions don't use up a fief's order. On the NES, a loan from the merchant leaves the order free; the PC-98 manual says the same of Grant orders for vassal fiefs and of the Other options. | p. 20 (PDF p. 12), Command 9 <Trade>, a) Loan | Manual |
| A daimyo has five abilities, health, drive, luck, charm, and IQ. At setup the player's daimyo can start no higher than 109 in each, and play can raise them as far as 210. | p. 12 (PDF p. 8), Setting Daimyo Abilitiesp. 14 (PDF p. 9), Daimyo Abilities | Manual |
| Health falls every spring and whenever there is an epidemic, and a daimyo whose health reaches zero dies. A healthier daimyo is less likely to fall ill, and a sick daimyo can't give some commands. | p. 12 (PDF p. 8), Setting Daimyo Abilities, a) Health | Manual |
| The PC-98 manual says a daimyo falls ill when an epidemic strikes his country or his health is low; illness lowers health, limits his commands, and usually clears by the next season, though it can last two seasons or more. On the NES, a sick daimyo can't move. | p. 19 (PDF p. 11), Command 1 <Move> | Manual |
| Every spring each daimyo grows a year older and every health value drops by one point, and a daimyo whose time has come dies of old age then. High health can lengthen his life. | p. 16 (PDF p. 10), Game Events, Seasonal Events, a) Springp. 14 (PDF p. 9), Daimyo Abilities and Fief Conditions, 1. Agep. 14 (PDF p. 9), Daimyo Abilities and Fief Conditions, 1. Age | Manual |
| Rest raises the daimyo's health. The player names how many seasons to rest, and the computer runs the game for him meanwhile, defending against any attack. The PC-98 manual caps a rest at 10 seasons, and says a daimyo whose home country falls while he rests dies, which ends the game. | p. 22 (PDF p. 13), Command 17 <Rest> | Manual |
| Plague can break out in any season. It lowers the daimyo's health, can kill a weak one, and reduces his men. | p. 17 (PDF p. 10), Natural Disasters, b) Plague | Manual |
| Typhoons come only in summer and lower a fief's rice output; a high dams value limits the damage. | p. 17 (PDF p. 10), Natural Disasters, a) Typhoons | Manual |
| Fall is tax time. The rice and gold collected depend on the fief's output, town value, and peasant loyalty and wealth; the men must be paid and fed then, and leave if the fief can't support them. Debts to the merchant are taken from the gold in fall. | p. 16 (PDF p. 10), Seasonal Events, b) Fallp. 15 (PDF p. 9), 8. Debt | Manual |
| Military revolts come when army morale is low and the daimyo is unpopular, and peasant uprisings when peasant loyalty is low and the daimyo is unpopular. In the home fief the daimyo fights a revolt himself, and he can pay off an uprising or fight it. Fief 21, Kaga, in the 50-fief game and fief 4 in the 17-fief game never have peasant uprisings. | p. 17 (PDF p. 10), Rebellions | Manual |
| The main display shows a current market price, which changes through the year. The PC-98 manual says the year's base rate is set in spring, and that buying rice raises the rice price and selling lowers it. | p. 13 (PDF p. 8), Main Display I | Manual |
| When a neighboring daimyo is killed by peasants or dies of sickness, the game asks the player whether to bid for his land, paying from the home fief's gold. | p. 17 (PDF p. 10), Game Events, 4. Bidding | Manual |
| A ninja hired with Hire can try to assassinate a rival daimyo; a large army or a high IQ makes the target hard to kill, and a failed attempt will probably still lower his health. | p. 21 (PDF p. 12), Command 10 <Hire>, b) Ninja, 4) Assassination | Manual |
| An attacker who wins takes the losing fief, and all the loser's vassal fiefs too if the losing daimyo was in it. A defender who wins keeps the soldiers, rice, and gold the loser left, and all the attacker's vassal fiefs if the attacking daimyo was killed. | p. 27 (PDF p. 15), After the War | Manual |
| In battle the defender places its units first, anywhere on the map, and the attacker places its own near the fief it attacked from. Each day the defender gives one command to each of its units, then the attacker does, and a day passes. | p. 26 (PDF p. 15), Troop Deployment and Combat: the foot of the left column and the right column | Manual |
| A war ends when one side runs out of rice, loses its command unit, or retreats. If the battle doesn't end within a month, or both sides are destroyed at once, the defender wins. | pp. 26-27 (PDF p. 15), Victory | Manual |