The game follows the series' standard level-based gameplay during the 21st century, as well as the open world gameplay set in 18th-century colonial America. The player has access to a huge wilderness known as the Frontier (which is 1.5 times bigger than Rome in Assassin's Creed: Brotherhood), the cities of Boston and New York; portions of the Eastern Seaboard and Caribbean Seacan be explored via the flagship of the Assassin's navy, the Aquila, captained by Connor himself, with Robert Faulkner his first-mate advising and teaching him in the ways of the sea.
Free running has been simplified to allow for more fluid parkour in the cities and wilderness, such as climbing and running on trees, mountains, cliffs,etc. Close combat has been modified, allowing Connor to dual-wield weapons and take down multiple opponents at once and players no longer need to manage the lock-on mechanic. Aiding this, Connor has access to a wide range of weapons which include muskets, pistols, native weapons such as the tomahawk and bow and arrow, a rope dart (used to pull foes or hang them, while on a tree) as well as the hidden blades. Human shields can be used against firing lines of enemies. Medicine is no longer used as health recovers automatically. Stealth is also revamped, allowing players to use natural elements such as tall grass and trees to hide, along with the ability to blend between any two people.
Assassin's Creed III features new weather simulations such as snow, fog, and rain. The seasons can also change i.e., Summer and Winter, which not only effect visuals but also gameplay, as the player will find running slower in deep snow. Snowfall can reduce visibility for the player and enemies, aiding stealth. Unlike the past games, this one includes animals varying from domestic (horses, cows, dogs) to wild (deer, wolves, bears). The wild ones are found in the Frontier, and can be hunted for meat or marrow in order to be sold. The quality of the kill determines the price, encouraging the player to hunt silently. For this, traps and bait can also be used.
Economy is now based on the Davenport Homestead, which also acts as Connor's adopted home. The site can be visited by people such as carpenters, tailors etc. suffering from displacement due to the war. Helping and interacting with these non-player characters (NPCs) will encourage them to settle in the Homestead. From there on, the player can craft various items and trade with them, and then sell the goods to the cities via caravan. The player can also help them build relationships with each other, which will then result in the formation of a small village. The player can also upgrade the Homestead manor as well as Connor's ship, the Aquila.
A revamped version of Assassin's Creed: Brotherhood's recruitment feature returns as players can enlist citizens to the Assassins' cause by completing "Liberation" missions. They also have a much larger skill set, which allows them to start a riot, provide a covert escort, act as a personal bodyguard etc. Other side missions include collecting Almanac pages, exploring underground tunnels to locate fast-travel stations, joining hunting and fighting clubs, investigating frontiersman rumours about UFOs and Sasquatch, "peg-leg" missions in which Connor goes to underground forts and wastelands to uncover the legend of Captain Kidd's treasure, and others.
Assassin's Creed III also features naval expeditions. Using Connor's warship, the Aquila, the player can navigate the high seas. Control of the ship relies on environmental factors such as wind direction and speed, local presence of storms, high waves, and rocks. Engagements are by cannon, with broadsides covering both flanks of the ship, and swivel guns that can be used to damage smaller ships which can also be boarded to find treasure. The Aquila is used in the side missions known as "Privateer missions" and is also used in some of the main missions.
The Wii U version of the game has extra features. The player has the ability to change weapons on the go and the map is always visible on the Wii U Gamepad. The Wii U version also supports Off TV Play. With this feature enabled, the main screen is redirected to the Wii U Gamepad.
Multiplayer returns in this installment by Ubisoft Annecy. Along with returning modes, new ones feature a co-operative mode named Wolfpack, in which 2-4 players are charged with killing certain NPCs within a time limit, through a sequence of 25 stages. It also features Domination, a team mode where players will have to capture certain areas of the map, protecting them from the opposing team.