can choose to engage in or not. Examples include scaring a group of bullies by pulling out a weapon, "settling" a fight between two civilians by killing one of them, or chasing down a thief who has just pick pocketed somebody. For the first time in the series, the player character, Arno Dorian, presents a unique set of abilities that can be upgraded through a skill tree system, enabling the player to assign points earned through gameplay to improve Arno's skills in stealth, melee, and ranged combat, as well as his health. Players are also able to customise Arno's weapons, armor and equipment to further complement their individual style of play. The quality of these items is indicated by their level, which can be a maximum of 5 (in the case of legendary gear). Players also have a wider selection of weapons available, including swords, axes, spears, rifles, pistols and throwable items, such as smoke bombs. The Dead Kings expansion introduces an additional weapon: the Guillotine Gun—an axe which has been converted into a grenade launcher. Like most previous Assassin's Creed titles, the game features an in-game economy system, which primarily revolves around the Café Théâtre, a former intelligence gathering front for the Assassins which has fallen into ruin and serves as Arno's main headquarters during the story. The player can renovate the Café by investing in upgrades, which change the building's interior and unlock new rooms, including a secret passage to the Assassins' underground hideout. The Café also functions as a passive business, producing revenue in the background which is deposited in a chest for Arno to collect; the more renovated the Café is, the more money it earns. Players can further increase their income by completing Café-related missions and purchasing additional taverns around Paris. Unity also introduces cooperative multiplayer to the series. Players can enter taverns, which act as social hubs in the game, where they can see if any of their online friends are playing the game at the current time. If they are currently in a mission, they will appear as a "ghost" version of their character, allowing the player to approach them to request to join their mission. If their request is accepted, both players enter the same game session, where they can continue the mission from the last checkpoint. Up to four players can play together at the same time. Each player takes on