Synchronization
Synchronization is the measure of your success in Assassin’s Creed Unity, with your performance in every activity – from a solitary collectible to a major main story Memory – contributing in some part to your overall progress. Essentially, it’s a representation of how much of the game you have completed, with 100% Total Sync being the ultimate goal. Almost every mission or task you engage in has a Synchronization score, which is added to your cumulative Total Sync rating (viewed on the Progress Tracker screen via the main menu) after you complete it.
Desynchronization
While Synchronization is a measure of success, Desynchronization is the consequence of failure. You cannot change the lives of the characters whose memories you explore, but must experience them with a respectable measure of fidelity. Diverging too radically from the “true” course of events causes Synchronization to be lost – and a swift return to a previous checkpoint.
Desynchronization can occur under the following conditions:
Death: This occurs whenever the Health Bar is reduced to zero. This happens most frequently in combat situations, but is also the result of falls from great heights.
Failed objectives: Failing to comply with critical mission parameters will lead to a return to a previous checkpoint.
Moving out of bounds: Attempting to visit a specific locale before the appropriate time, or moving outside the confines of a current mission area can cause a loss of Synchronization. There is a clear visual cue that provides a strident warning whenever you approach such boundaries (
). Take heed, and move away swiftly.
Anomalous behavior: If you assault inappropriate targets (such as allies or civilians), Desynchronization will occur if you persist after ignoring an initial message of admonishment.
Challenges
In addition to mandatory objectives (such as avoiding detection or assassinating a target), many main story missions and side quests also feature optional Challenges. On one level, these exist to encourage a certain style of play that befits the nature of a mission: to make players surrender the assassination abilities and attempt a bloodless infiltration of a heavily guarded area, for example. Others function as a more direct test of your prowess, such as the completion of a specific task or the use of certain tools.
The main reason to complete Challenges is to increase your Total Sync rating. If this isn’t important to you, or you would prefer to return to complete a Challenge at a later date, there is absolutely no penalty for failure.
Progress Tracker & Memory Replay
The Progress Tracker option in the main menu enables you to study your progress in all main story missions and side quests (
). You can also check individual Memories to find instances where you are missing a Challenge, and replay them if you wish. The Replay option moves Arno back in time and launches the mission immediately.
Hold 
/
to jump to the end of cutscenes. Note that certain cinematic sequences (such as short establishing shots or transitions) cannot be skipped.
You must complete an entire Memory and wait to be returned to the Progress Tracker menu for Challenges to be recorded. Partial playthroughs do not count.
