In Haven City, the alarm system was a security implementation enforced by the Krimzon Guard during Jak II. Certain criteria would set off different levels of immediate responses where at least each on-foot patrol unit would pursue and kill or arrest the perpetrator, or in the case of a larger-scale attack, battle the opposing faction (e.g. the assault by the Metal Heads in Act 3 of Jak II).
The alarm deactivates after a relatively short period of time passes without the subject being caught or killed. It was either deactivated or damaged after the assault on Haven City shortly before Jak 3, and was subsequently no longer functioning during that time and afterwards.
Minor offenses included killing a citizen, attacking a guard (melee, weapon, or JET-Board), or opening fire (on a guard or a citizen). Only guards which were patrolling on foot would respond to minor offenses, while vehicle units would continue patrolling and typically ignore it, unless the threat escalated. Motion sensing turbo cannons would also activate during these offenses if the suspect came within their vicinity. Jak can still hijack Krimzon Guard vehicles at this level.
Elevated offenses, often codenamed "red fire", included colliding, shooting, or hijacking a Krimzon Guard vehicle, becoming Dark Jak, or certain missions in which guards were ordered to pursue someone, or when someone has continuously killed several guards. Differing from minor offenses, KG patrol vehicles also pursue the perpetrator, and some other guard lines are evoked different from minor offense scripts. Some characteristics distinguishing it from minor offenses include roadblocks, large-scale guard deployment from air trains, major collisions, in-city robot guard activation, or long-winded pursuits. At this level and past it, Jak can no longer take control of Krimzon Guard vehicles. Some missions trigger elevated offenses.
Major offenses could be triggered by Jak turning into Dark Giant, a war in the streets, or an unexpected assault. During major offenses, the alarm system does not typically deactivate. If it does, it takes much longer than that of a minor or elevated offense. All KG units are called to action during major offenses, and some rarer guard scripts are evoked. Some missions trigger major offenses.
Depending on the threat level, certain types of guards will become hostile and will indefinitely spawn until the alarm has stopped. Jak can still hijack Krimzon Guard vehicles on a minor alarm level until it becomes elevated. When sounded, the background music of the game changes to a more fast paced and suspenseful track and the minimap pulses red.
In addition to the infantry, several motion sensing turbo cannons across the city are activated and when the alarm is set off, they will often fire even after the alarm has been disabled. They are used to mainly take out vehicles but can be used to take out personnel as well. Beneath these cannons are switches that are linked to the city's eco grid, indicating that the cannons draw their power from the grid. These switches were important to Jak's entrance to the palace in Jak II when Vin routed the power from these machines into an unused elevator of the Palace's support tower.
Dying, entering an interior, driving long enough, lying flat against a wall out of sight of guards (though this might not be the best option; sometimes the guards still find you), and if the alarm is triggered through a mission, it may be removed upon completion.
- If you trigger the alarm system, enter the gun course facility, go to the back of the room (near the door for the gun course training) for a few seconds, and then exit the facility, the minimap will continue to pulse red and the suspenseful music will still play, but the guards will not chase after you.
- After Metal Heads break into the city, the alarm will go off continuosly. However, Krimzon Guards will not be chasing Jak and, instead, will be actively fighting against Metal Heads and protecting civilians.