Heat is a game mechanic in Shattered.
Heat is generally defined as how wanted you are by the police. Unlike most games with heat such as Watch_Dogs or GTA, in Shattered there isn't a heat level which shows how wanted you are. You are simply wanted, and the more civilians you kill and damage you cause, the more police you will have after you. Killing police officers will further increase this.
Heat can be broken up into two phases:
Phase 1: 911 CallEdit
that the player will hear the audio of a 911 call, and a few seconds after the 911 call ends, Phase 2 will start. Also note that if the crime is committed near police presence, phase 2 will automatically start without the 911 call.
Phase 2: Police in PursuitEdit
During this phase, the police have tracked James Derettas's location and police officers are being dispatched to the player's location. The amount of units deployed depends on how bad the crime was (how many people were killed, how many things were destroyed, etc.) as well as how far the player has progressed through the storyline. At first, Interceptors are dispatched to take James out but if one is destroyed during this process, Enforcers are sent instead.
Note that once you hear the 911 call, there is no way to stop it. The police will come for you but you can escape (see below).
Escaping the PoliceEdit
If the player can lose the cops, they won't lose them right away. The police will lose track on the protagonist but will remain looking for him. Police cars will drive slowly through the streets, shining their spotlights on parked vehicles and dark spots during nighttime. Foot patrols will appear and depending on how wanted the player is, a police helicopter will help look for the player and roadblocks will be established.
A percentage will appear near the heat meter while the police are looking for the player, starting at a certain percentage depending on the player's heat level and story progress. This percentage will slowly drop to zero, and once it does, James is free. Success!
In Chapter I the police are noticeably more aggressive towards James, since he is new at the time and do not like him. In Chapter II this dies down a little bit and by Chapter III James has turned the police innocent again rather than corrupt, and has earned the ICPD's trust back. Thus, the cops aren't as aggressive towards James but are at the same time since James has become more powerful. Make sense?