100man-nin no Nobunaga no Yabou

100man-nin no Nobunaga no Yabou (100万人の信長の野望, Hyakuman-nin no Nobunaga no Yabou; Literally: "One Million People's Nobunaga's Ambition") is a social game adaptation of the Nobunaga's Ambition series. It is Koei's first social game to be based on a preexisting IP.

As of August 26, 2013, the social game has over 2,300,000 registered players. The company thanked fans and users when it reached two million with a special campaign and Nobunaga portrait. A similar log-in event was held to commemorate 1,000 days of service.

Gameplay
The game's controls are simple. Players simply tap the touch screen (smartphones) or use the left-mouse button (PCs) to confirm their commands in the game. The game is played in real time, and timers are needed for nearly every action in the game.

Each player begins the game selecting which daimyo, or warlord, they wish to serve. Ruling daimyo rotate with each season. Ninety different daimyo are available when the season begins, but their numbers dwindle quickly as players lay siege on one another. New players join whoever remains in the running at the time of their registration. Here are the daimyo who are still competing in this season:
 * 1) Katsuie Shibata
 * 2) Nagamasa Azai
 * 3) Yukimura Sanada
 * 4) Masamune Date
 * 5) Shingen Takeda
 * 6) Ujiyasu Hōjō
 * 7) Ieyasu Tokugawa
 * 8) Kenshin Uesugi
 * 9) Nobunaga Oda
 * 10) Yoshihiro Shimazu
 * 11) Mitsuhide Akechi
 * 12) Motochika Chōsokabe
 * 13) Sōrin Ōtomo

Loyalty for a lord can be changed at the player's discretion once per day. If the player's current lord happens to lose their territory, he/she will flee. During their flight, they are momentarily absent from the map and are given several real-time hours to recover. If any player chooses to serve the fleeing lord, the clan can revive and stay within the running. When a lord is left completely without players' support, his/her clan is abolished. Each clan additionally has "Revival Points" to limit the number of restorations available; loyal followers are given the task to prevent these points from ever being used.

The player's goal is to end a season, or achieve complete unification of the land's ninety castles under one of these daimyo. The end of one season begins the birth of another. If a season proceeds for too long, a conqueror's cup is held to decide the final victor. Clans engage in a one day tournament until only the one with the most power wins.

After completing the game's tutorial, the player must either balance their actions between governing their land or fight against other users in the name of their lord.

Each player is given a plot of land in their lord's territory. They can live near either one of his/her ruling castles to defend it. Similar to its parent series, the player can build various facilities to help supply for their troops. Crops, for example, can provide troop supplies and barracks can supply troops for the player's army. Each building requires generals, time, revenue, and the player character's energy for its completion. Commands to benefit from these establishments also requires an energy limit. In most cases, three commands can be issued per real-time day; energy is fully restored at midnight (JST).

More facilities can be built and upgraded based on the player character's level, or "Lord Level". Players can increase their Lord Level by winning castle sieges. Once the player selects an enemy castle they wish to topple, a single click initiates an automated battle; results are reliant on the army's troop numbers and general capabilities. Gold and experience are the rewards for each victory.

Each castle requires an allotted number of victories to breech its defenses. The moment the castle falls, the defenders will stage a desperate last stand and duel the player's character. Victory for the player causes the enemy forces to fall; defeat gives the defenders a chance to rebuild their castle. Win or lose, a real-world time limit determines the next time the player initiate another battle.

Live updates regarding changes in territory are frequently announced to players. Veteran players can lead guilds under a specific lord to help ally users. Friendly players who join these guilds can provide back-up support for members in their endeavors and be rewarded with minimal gold for their efforts. These miniature communities may also act as a referral list for the game's special friend campaigns.

Mobage Coins (virtual currency) can be used to instantly restore lost troops or lost energy. Healing items can be purchased with Mobage Coins yet saved to generate a similar effect.

Generals
The game's visuals heavily borrows from the series's latest title, Tendou. Select characters, however, have different portraits based on other company franchises or from completely different time periods of Japanese history. New portraits can be added into the game based on the game's various special events.

The player can obtain generals by collecting introductory letters to summon them to their side. The player can initially keep ten characters at a time, but this number can increase based on their levels. Earned generals, even those which are discarded, are categorized and recorded in the game's character log.

Four main traits determines each character's usefulness to the player:
 * Troop Type - army the character will lead into battle. The troop types are infantry, riflemen, and calvary. Infantry tops calvary, calvary bests riflemen, and riflemen destroy infantry.
 * Domestic - efficiency for creating and benefiting from facilities.
 * War - battle competence and strength of their respective troop type.
 * Formation - determines the maximum number of troops general can bring into battle.

Generals can be strengthened by fusing character cards together for experience. The player can boost the merging process with additional items either earned or purchased at the shop with Mobage Coins. As the character levels up, the maximum limits of their attributes climbs. Equipment or accessories can also increase stats, but the effects only last until the item breaks. Scrolls to grant special abilities can be used at the player's discretion.

Rarity is noted by the rank on each character card; higher ranks are often reserved for famous figures of the era. Rarer cards often require the player to hire a group of affiliate officers to obtain them. These groups are called "Character Collections" and they vary with the individual.

Related Media
Hyakuman-nin no Nobunaga no Yabou has had crossover events with the following games or sources: Newcomers who start playing the Yahoo!Mobage version in mid-December 2013 can receive a commemorative Christmas box set.

One of the events for celebrating 30 years of Nobunaga's Ambition includes hosting an all Nobunaga event in Hyaku-man nin no Nobunaga no Yabou. There are sixteen different Nobunagas available (including the default one within the social game). The following Nobunaga personas can be earned by players in this social game:
 * 1) Nobunaga's Ambition series - Nobunaga no Yabou Returns, Nobunyaga no Yabou, Nobunaga no Yabou Online Tenka Mugenshou, Nobunaga no Yabou Internet, first Gameboy edition of Nobunyaga no Yabou, sprite used on the pavement in Koei-Tecmo's courtyard, Nobunaga no Yabou Souzou, Nobunaga no Yabou ～Rin-ne～ manga.
 * 2) Taikou Risshiden V
 * 3) Samurai Warriors 3
 * 4) Geten no Hana
 * 5) Inindo: Way of the Ninja
 * 6) Toukiden
 * 7) Kessen III (younger version)
 * 8) Ikuso no Ko - Oda Saburo Nobunaga Den manga by Tetsuo Hara

People who visit the Seki Sword Tradition Museum during the span of the collaboration could obtain a serial codes which can be used to obtain a free alternate version of Nobunaga –whose portrait matches the social game's main visual– and Magoroku Kanemoto, a blade named after a famous swordsmith. An in-game event dedicated to the museum's history granted players the opportunity to win rare swords from Gifu.

Koei-Tecmo has sponsored two special written exams for two historical figures. The first was a Nobunaga themed one called Nobunaga Sengoku Rekishi Keitei. The second is known as Sanada Sandai Sengoku Rekishi Keitei, which focuses on the historical exploits of figures found within the famous generations of the Sanada clan: Yukitaka, Masayuki, Nobuyuki, and Nobushige. People who sign up and arrive at the site can receive serial codes for three Koei titles. The first test offered Kipposhi Oda, and the Sanada exam offers Nobushige Sanada.