From [**The Long Guide** by Frankelstner](http://steamcommunity.com/sharedfiles/filedetails/?id=267214370#307643 "PD2 - The Long Guide - Domination") - detailing stealth mechanics analyzed from the extracted game files:</sup> Terms used: - "**Cool**" refers to the state of person or camera during stealth when he/it has no exclamation mark. - Once the person or camera has an exclamation mark or alarm goes off, there is no going back: The subject can never become cool again. I refer to this state as "**uncool**". Dead or broken subjects are not included. **** ###Stealth - Alerts Alerts are noise and instantly turn people in hearing range uncool. In the context of this game, alerts mean that neither the orientation of the head nor obstacles make any difference and that the person becomes uncool instantly without becoming suspicious first. ###Human observers become alerted by the following: - Glass breaking (range: 12 m) - ECM feedback (range: 100 m) - Gunshots (range: 25 m when enemies shoot, usually 45 m with player weapons) - Gunshot impacts (range: 1/4 of the gunshot noise) - Grenade/Flashbang explosions (range: 100 m) - Trip mine explosions (range: 50 m) - Taking fall damage (range: 2.5 m) - Civilian screams upon becoming uncool and at various other times (range: 2 m) - Footsteps by a sprinting criminal (range: 4.5 m, sometimes 4.5 m * sqrt(2) = 6.4 m) - Civilian or enemy screams when experiencing moderate or heavy hurt or death (range: 6 m for clients without Shinobi aced, 0.25 m with Shinobi aced, 0 for host without Shinobi aced). Even handcuffed guards scream. In contrast to the other noise sources, footsteps require line of sight: They do not propagate through solid walls, but they do propagate through glass. Just sprinting for a split-second is enough to alert people. The origin of the noise is your first-person camera. Unless you shoot in the sky, every gunshot ends with a gunshot impact. The noise origin is the impact location. If your gun has issued a gunshot alert (i.e. you have fired your gun), subsequent gunshot alerts by the gun will be blocked for 1.5 seconds, unless the origin of the alert differs by more than 5 meters. Whether you fire your CAR-4 once or 15 times to control civilians with Control Freak, they both issue just a single gunshot alert. There is a separate but pretty much identical block for gunshot impact alerts, where the 5 meters rule has a greater effect. All player weapons have an alert range of 45 meters with the following exceptions: Brenner, KSP and R93 have an alert range of 40 meters. The Thanatos has a range of 35 meters. The saw is a gun like any other and has an alert range of 35 meters when not using up the blade, else 150 meters. All weapons with an alert range of 45 meters have their alert range reduced to 1 m when silenced (thus their gunshot impacts have a mere 0.25 m range). Weapons with an alert range of 40 meters or less have their alert range reduced to 0 when silenced (i.e. R93 and Thanatos). **** ###Stealth - Alarm There are 4 different ways alarm can be raised: - An uncool person (guard or civilian or gangster) calls the police. - A camera is uncool. - A pager is left unanswered or answered unsuccessfully. - Map-specific triggers. Usually motion sensors (lasers) or alarm buttons. Basic ECMs disable the first two triggers as long as they are active. With the ECM pager skill, alarm is raised only by map-specific triggers. There are three ways to figure out if alarm has been raised: - All exclamation marks suddenly disappear simultaneously despite the enemies still being alive. - A text message appears on the screen. Some map-specific alarm triggers do not show any message at all (Rats day 2, Big Oil day 1, Firestarter day 1, Framing Frame day 3), or are otherwise incorrect (alarm buttons on Trustee bank). - The music changes. On Big Oil especially, if you are not the person stealthing it, the only reliable method of figuring out if there has been alarm is paying attention to the music, as there is no alarm message and the disappearing exclamation marks might be due deaths. Conversely, as long as you can see a single exclamation mark, you are still in stealth as no alarm has been raised yet.