Synchronization

Synchronization (or, for short, Sync) is Assassin's Creed's equivalent of a health meter. Since the events experienced by Desmond in the Animus have already taken place in the past, Synchronization is a measure of how synchronized Desmond's actions in the Animus are with the actual events in the past. If all Synchronization is lost, the simulation restarts from an earlier point.

The Sync meter
Synchronization is measured by a bar in the top left corner of the HUD, dubbed the "Sync meter" or "Sync bar". This bar will display the current level of synchronization.

The Sync meter can be turned off in the Options menu, as well as all other HUD elements.

Loss of Synchronization
If Synchronization reaches a critically low level, the screen will begin to flash blue and red to warn the player. If all Synchronization is lost, then the simulation will restart from an earlier point.

Synchronization can be lost for several reasons:
 * killing of innocent civilians (breaks the First Tenet of the Assassins' Order)
 * being hurt in battle
 * drowning (always instant death)
 * jumping or falling from a great height (an extremely long fall may prove fatal)

Any lost Synchronization will recover over time.