Assassin's Creed II: Discovery is a side-scroller game wherein players assumed the role of Ezio Auditore da Firenze. Primarily set in Italy, Ezio navigated through the game's levels and accomplished specific goals prior to the mission.
As well as this, Ezio was able to scale most buildings by its side only, and could also roll, jump, and swing through the environment. Likewise to the previous installments, enemy guards were present within the game, which Ezio could either avoid or confront, depending on the player's choice and the current situation. Several guard archetypes were present within the game, such as the Halberd Guards (a stationary version of the Seekers), Captain Guards (a more agile variation of the Brute), archers and many others.
In terms of weapons, Ezio had his father's Hidden Blade at his disposal, alongside a sword and throwing knives. Ezio could then utilize all of these against hostile targets to dispose of them, either in an open or covert manner. Likewise to Assassin's Creed II, Ezio could assassinate guards by pulling them down from ledges, as well as hiding using bales of hay, with the addition of new hiding spots such as wooden barrels and obscure open spaces.
Combat in the game was similar to the previous Assassin Creed titles in a number of ways. When engaging in sword combat, players could execute chain attacks which break the defense of the enemy guards, and also perform counterattacks, which could result in an instant kill or allow for a brief moment to attack. Accompanying this, players could perform a clash with a target, which resulted in a test of strength, complete with a pressure bar at the side of the display. Players then had to fight the guard's resistance in order to incapacitate them, or else Ezio would take damage.
Memories were played out in missions, similar to Assassin's Creed II, in that players were given synchronization points by clearing the mission, provided the required objectives were met in the mission's structure. These specific factors were the following: Time cleared, kills, damage taken, and notoriety. In order to achieve perfect synchronization with the requirements, the player had to complete the level as fast as possible, kill as many as they could, and take minimal damage respectively, though the required values varied from mission to mission.
There were several mission types set in a specific memory, which defined how Ezio should have approached them, or the mission would be a failure. In all, there were three mission types in the game:
- Normal - Players could approach the mission however they liked and take their time to explore the environment for collectibles, however the basic mission factors were still present.
- Chase - Players had to run towards the objective whilst trying to avoid combat with any hostile enemies, determining the best route to reach the objective with speed. The player was followed by a rain of arrows that could only be avoided once Ezio was indoors or in a hiding spot.
- Stealth - Players were required to avoid open confrontation with hostile enemies at all costs, resorting only to using a stealth execution move. Enemies were indicated by arrows that appeared whenever Ezio was near to them, and the player was permitted to be spotted 3 times in total. Exceeding the given limit would result in the mission being a failure.
There were also challenge rooms present in the game, which required Ezio to clear a specific objective. The challenge rooms were played through in the Animus corridor, similar to the tutorial levels in the game. Cheats, dubbed "Animus hacks", were present within the game, which could be unlocked by obtaining enough synchronization points. These cheats ranged from character skins to boosted gameplay movement and perks, which gave the player an advantage or allowed them to customize Ezio.
However, only one hack could be used at a time, and once a level was finished with a hack activated, the level wouldn't continue automatically to the next, instead returning the player to the level menu.
Collectibles were also present in game, with there being a total of 5 different variations: Memory paths, which could be used as a guide to show a player where to progress; Renaissance maps, which unlocked the aforementioned challenge rooms; Knives, which refilled Ezio's throwing knives supply; Wanted posters, which could be torn off to increase the health meter once the required amount was met, and finally art pieces, which could be collected by unlocking hidden rooms in missions.
The iPhone and Nintendo DSi versions of the game allowed the player to integrate their facial likeness into the game through photos, replacing Ezio's placeholder image in the wanted posters with the player's own image. Also, the art pieces found in the iPhone version could be imported for use as wallpapers.
In the year 1491, while in the midst of searching for the Apple of Eden, the Assassin Ezio Auditore da Firenze was summoned by the Venetian Thieves Guild leader Antonio de Magianis to assist in the dilemma of his contact from Spain, Luis de Santángel. Representing the navigator Christopher Columbus, Luis asked Ezio for his protection, fearing that the company he kept bore ill fate against him. Though reluctant at first, Ezio agreed to assist, once he heard of Christoffa's connections with the Spaniard, Rodrigo Borgia.
Luis' suspicions proved right, and Ezio intercepted the planned assassination attempt of Christoffa, before pointing him to safety as he fled the meeting place. The two would then meet up again at Venice's garden district, along with Luis. There, they asked Ezio to recover an atlas for their expedition in their hostel, which contained important maps that detailed vital routes. As a final favor, Ezio agreed and successfully intercepted the atlas, before he handed it to the two.
Before setting off for their expedition, Luis informed Ezio about the status of the Spanish Assassins Guild, who were all apprehended by Tomás de Torquemada and the Spanish Inquisition. When asked by Ezio how he knew of the Assassins, Luis mentioned to him that he was well-connected.
Returning to Antonio, Ezio announced that his search for the Piece of Eden was postponed, believing that it was his duty to help reform the Brotherhood in Spain. Following this, Ezio left the Thieves Guild in Venice and set off to start his search for the Assassins in Barcelona.
After some brief trouble with a French rogue, Ezio searched for the Spanish Assassin members, which led him to the Assassin Guild, only to find himself ambushed. After fleeing into the underground sewers to avoid the soldiers who have surprised him, Ezio encountered a member of the Assassin guild, Raphael Sánchez.
After an introduction, Raphael informed Ezio that the Spanish Assassins were apprehended by the Inquisitor Gaspar Martínez, and that he should go and meet with him if he was to learn more. Leaving the underground area, Ezio infiltrated the quarters of Martínez, and there the man denied holding Assassins prisoner, yet admitted that one of them was to be burned at the stake. After learning this, Ezio assassinated Gaspar, and took a list of names from his body. From there, Ezio left to save the Assassin.
Evading most of the guards, Ezio was able to save the Assassin, before he met with Sánchez to discuss the list that he had found. After reading the scroll, Sánchez concluded that the names were possibly a list of targets tied to the Spanish Inquisition. In order to eliminate them, Ezio and Sánchez traveled to Zaragoza to seek out the Inquisition's calificador, Pedro Liorente. Arriving at Pedro's location, Ezio witnessed the murder of an Assassin by the order of Pedro Liorente and Tomás de Torquemada, whose orders came directly from Rodrigo Borgia himself, and vowed to free the remaining prisoners before they too are executed.
Despite increased security, Ezio rescued the imprisoned Assassins and assassinated Pedro Liorente after he denied the Templars' existence. Returning to Raphael with the news, Raphael revealed himself to be the Treasurer to Queen Isabella and that the Assassins have been combating a Templar scheme in the form of the Inquisition and their hope of ridding Spain of all the Moors. Coming to Granda, Ezio learned of Luis Santangel's working in the King's court and was tasked with finding a Templar spy and a passage into the besieged Alhambra palace. The Spanish Assassins began to suspect that the Templars are planning their own expedition west to uncover the New World. Ezio made his way inside and discovered that the Templars have been keeping King Muhammed XII prisoner to purposefully prolong the siege and drain the Queens' resources on the ongoing war. Ezio freed King Muhammed XII and carried the news of his abdication.
As retaliation for upsetting the Templar plan with the Moor King, a new round of arrests and executions has been ordered by Tomás de Torquemada. Ezio prevented some arrests and assassinated the Inquisitor in charge of the operation, Juan de Marillo.
After hearing the news of the war ending and King Muhammed XII and Queen Isabella meeting to discuss terms of his surrender, Christoffa threatened to indulge other offers to sponsor his journey if the Queen doesn't act fast to give him an answer. Not being satisfied that the Queen was still uncommitted to his cause, Christoffa headed to Paris, France to accept an offer from King Charles. Ezio found Cristoffa on route to France and protected him from another attack and convinced him to return to Queen Isabella as she has changed her mind thanks to counselling from Luis Santangel and Rapheal Sanchez.
After Christoffa successfully launched his exploration voyage, Tomás de Torquemada dispatched Inquisitor soldiers to murder Luis Santangel and Rapheal Sanchez as revenge for their disruptive counseling to the Queen. Ezio was successful in preventing both attacks and tracked down Tomás de Torquemada in hopes of learning about his ties to the Templars. Upon finding and confronting him, Ezio learned that the Borgia is one of three Papal candidates this year, but with the assassination attempt unsuccessful, he returned to the other Assassins to share that Tomás de Torquemada did not seem to be a Templar himself and that it was probably for the best that he wasn't able to assassinate him as his death would have caused more turmoil than it ended.
- Despite the storyline occurring between the two DLCs for Assassin's Creed II, Ezio does not possess dual Hidden Blades. The single blade used in the game is the basic one, with no Poison Blade or Hidden Gun upgrades.
- Similarly, the beard which Ezio grew after the Battle of Forlì is not present as well.
- 在Reddit的全民问答上，Aymar Azaizia，游戏系列内容负责人证实《刺客信条II：探索》与《刺客信条》电影没有任何关连。然而，他之后改变了主意，并再次宣布两者是有关连的。
- Archers could not face Ezio during a close quarters confrontation. Once Ezio got within melee distance of an archer, they would surrender and ask for mercy.
- If an archer was attacking Ezio, attempting to assassinate him would result in Ezio grabbing an arrow from the archer and stabbing him with it, rather than using his Hidden Blade.
- Guard Captains appeared in the game and resembled the Brutes in Assassin's Creed II and Brotherhood. However, they were extremely fast, agile, and devastating. If Ezio attempted to jump onto a wall, they would also jump and try to pull him down.
- Counter-attacks were very effective when Ezio was surrounded by soldiers that dealt light attacks, but counter-attacking could not be used against Guard Captains, as they could break Ezio's defense in one strike.
- Pike guards appeared in the game, resembling Papal Guards seen in Brotherhood. They focused on defending specific locations however, and did not pursue Ezio.