====== Doors ======
[{{ :doors:closed_door.png|A closed door.}}]
[{{ :doors:open_door.png|An open door.}}]

**Doors** allow passage from one room to a neighboring room. [[:Agents]], rescued [[:Couriers]] or [[:Prisoners]], and [[:guards]] can all open and close doors. When closed, doors are impassable and provide [[:cover#hard cover]].

Agency controlled units can open and close doors when orthogonally or diagonally adjacent to them; [[:guards]] can only open and close doors when orthogonally adjacent to them. In addition, [[:agents]] can install [[:items:Shock Traps]] on all kinds of doors when orthogonally adjacent to them.

Usually, when [[:agents]] or rescued [[:Couriers]] or [[:Prisoners]] open or close doors that [[:guards]] can see, the [[:guard]] will [[:guard_behaviour#interest point|notice]] the door opening or closing on the side it was opened or closed on. This will happen even if the tile the door is adjacent to is in [[:cover#soft cover]], as doors do not receive soft cover. Hacked [[:guards#drones]] and [[:agents:Archive Prism]] in disguise can open and close doors without causing [[:guards]] to be interested.

Human [[:guards]], when not [[:guard_behaviour#alerted]], will usually leave doors in the condition they were in after they move through them. The only exception is when they open a door to perform a [[:peeking|peek]] or when they are [[:KO|KOed]], [[:lethal_damage|killed]], or [[:guard_behaviour#alerted]] before they have the chance to close the door. [[:Guards#Drones]] and all [[:guard_behaviour#alerted]] guards will always leave doors open when moving through them.

[[:Guards]], when [[:guard_behaviour#alerted]], can in some conditions destroy closed doors, rendering them permanently open and dealing 1 [[:KO]] damage to any unit on the other side. [[:Agents]], [[:Couriers]] or [[:Prisoners]] [[:KO|KOed]] in this way will also start the next turn with 0 AP if they were not [[:pinning|pinned]] before waking up. This can only happen when the guard's [[:guard_behaviour#interest point]] is one tile beyond the door from the guard, and it usually happens because the guard [[:guard_behaviour#interest point|noticed]] an [[:agent]] close it. An [[:guards:Akuma Drone]] can also be [[:firewalls|hacked]] to "kick" down doors as well.

===== Lvl1 Security Doors =====
[{{ :doors:lvl1_security_door.png|A locked Lvl1 Security Door.}}]

**Lvl1 Security Doors** are doors that cannot be opened until they are unlocked by a [[items:Lvl1 Security Passcard]], [[:agents:Banks]]'s [[:augments:Crypto Computer]], or a [[:items:Lock Decoder]] after 2 turns. [[:Guards]] cannot unlock these doors, nor will they try to path through them until they are unlocked.
Banks can unlock the doors when she is either orthogonally or diagonally adjacent to them. The Lock Decoder can be placed only by an agent who is standing orthogonally adjacent to the doors.

Note that with the exception of the Lvl1 Security Door that guards the [[:missions:Security Dispatch#Secure Locker]] in [[:missions:Security Dispatch]] missions, there is always an alternate route to the other side of a Lvl1 Security Door.

===== Vault Door =====
[{{ :doors:vault_door.png|A Vault Door.}}]

**Vault Doors** are doors that cannot be opened until they are unlocked by a [[:items:Vault Access Card]]. They will only appear in [[:missions:Vault]] missions and some [[:missions:Cybernetics Lab]] missions. They will always be found in the [[:facility#Objective rooms]] of these missions, and need to be unlocked and opened to access additional loot.

===== Exit Door =====

**Exit Doors** cannot be opened until they are unlocked by a [[:items:Exit Access Card]]. They appear in [[:modes:Endless]] modes from day 5 onwards, in all facilities. Unlocking the Exit Door is required to reach the [[:facility#exit room]] and complete the mission.

===== Guard Entrance Doors =====

Two **guard entrance doors** block the way to [[:facility#guard entrance]] rooms. These doors cannot be opened by agency-controlled units, and automatically close once [[:guards]] pass through them, even if a [[:guard]] would not normally close a door in that situation. As such, it is not normally possible for an [[:agent]] to enter [[:facility#guard entrances]].

It is possible to set up a [[:items:Shock Trap]] on these doors.
===== Strategy =====

Navigating between rooms of a facility is a core part of Invisible Inc.'s gameplay. Doors are the most common bottlenecks in Invisible Inc., both for [[:vision]] and for navigating the facility, so a lot of Invisible Inc.'s strategy comes down to using doors effectively - maximizing your vision and mobility, and minimizing that of the [[:guards]].

The best strategy for the player depends heavily on what game [[:mode]] you are on. When playing a higher difficulty than you are used to, you may need to unlearn strategies that worked on lower difficulties.
==== All difficulties ====

   * When opening a door to a new area, it is almost always right to either [[:peeking|peek]] through it first or open it from a tile diagonally adjacent to it. Otherwise, you run the risk of being immediately seen by a [[:mainframe_devices#Security Camera]] or [[:guard]].
   * It's a good habit to always close doors after moving through them, as doors left open can leave unexpected sight lines for guards to see your [[:agents]] later. Random doors being open tends to favor the [[:guards]] over the player. There are a few exceptions, primarily in situations when a [[:guard]] will notice the door being closed, but closing the door should be the default option.
   * If a [[:guard]] sees the door you're about to open, consider waiting until next turn to open it - he may patrol away, allowing you to open it undetected next turn. Simply opening the door (from a diagonally adjacent tile), luring the [[:guard]] in, and [[:KO|KOing]] him is also a viable option, but it is better to avoid disturbing the guard at all.
   * If no [[:guard]] sees the door you're about to open, you can freely open the door and then [[:peeking|peek]] again to get a more complete picture of the next room, and allow you to hack [[:mainframe devices]] there.
     * On difficulties below [[:modes:Expert Plus]], you can be sure no [[:guard]] will notice the door if the tile in front of it is not "Watched", "Noticed", or "Hidden".
   * If you decide to open the door to lure a [[:guard]] in for an [[:attacks#ambush]], you have two options:
     *  1) Stand in front of the door for the ambush. 
       * The advantage of this is that even if the [[:guard]] sees other [[:agents]] when opening the door, they will be [[:KO|KOed]] before they can react.
       * Do not stand in front of the door if the [[:guard]] is [[:guard_behaviour#alerted]]! This will result in the [[:guard]] kicking the door down and [[:KO|KOing]] your [[:attack#ambush|ambushing]] agent. Depending on how the [[:guard]] is coming in and what [[:cover]] is available next to the door, it may be possible to [[:attack#ambush]] alerted [[:guards]] in this way by leaving the door open.
       * This method also runs a higher risk of another [[:guard]] seeing the lured [[:guard]] be knocked out than the other method. If this happens, the witnessing [[:guard]] becomes [[:guard_behaviour#alerted]]. In addition, since you're right in front of the door, it's quite likely he [[:guard_behaviour#overwatches]] you this turn.
     * 2) Stand diagonally adjacent to the door for the ambush
       * You will need to ensure that no [[:agents]] are immediately visible when the [[:guard]] opens the door; otherwise the [[:guard]] will [[:guard_behaviour#overwatch]] them before falling for the trap.
       * There are not as many sight lines for another [[:guard]] to see the lured [[:guard]] be knocked out, and even if they do, they're much less likely to [[:guard_behaviour#overwatch]] the [[:attack#ambush|ambushing]] agent since they're in [[:cover]].
   * In some worst-case-scenarios, it can be worth it to be deliberately be [[:guard_behaviour#overwatched]] by a [[:guard]] through a door. Though being [[:guard_behaviour#overwatched]] is always dangerous, being [[:guard_behaviour#overwatched]] through a door is less dangerous than other situations, as the [[:guard]]'s vision into your room can be limited, allowing plenty of options for escape. In addition, the door can often just be closed to escape.
     * You can even use the fact that [[:guards]] will not move after [[:guard_behaviour#overwatching]] to use a door as a chokepoint in certain conditions - if a [[:guard]] can see an agent before moving through a door, they will not move through the door. The developers gave [[:guards]] the ability to kick down doors to make these kinds of tactics less effective, but this can often be circumvented by distracting the [[:guards]] after closing the door using methods such as [[:sprinting]], causing them to not kick the door down.
==== Experienced and up ====

On [[:modes:Experienced]] and higher difficulty, [[:guards]] will have longer patrols that often go through a door, and they can patrol into the [[:facility#Starting room]]. This makes doors more dangerous to the player than on [[:modes:Beginner]]. 

   * On turn 1, your first task in the mission is to assess how to protect your [[:agents]] from being seen by [[:guards]] any guards entering the [[:facility#Starting room]]. This can be done by using [[:cover]], [[:attack#ambushing]], or sometimes with early exploration. If you have enough AP to do so, [[:peeking]] into the next room(s) is a good idea, though you should have a plan if the door is not safe to open. If no [[:guards]] enter the [[:facility#Starting room]] on the first turn, it's (probably) [[:guard_behaviour#patrolling|patrol]]-free, and you can use AP more liberally.
   * When [[:peeking]] into a room for the first time, it's a good idea to maintain the peek through the door through the [[:corporation]]'s turn to observe the room for a full turn. This will allow you to know whether there are any [[:guards]] who [[:guard_behaviour#patrolling|patrol]] through doors into that room.
==== Expert Plus ====

On [[:modes:Expert Plus]], you can no longer be sure that a door is not seen by a guard when [[:peeking]] through it while closed. 

This means that you will always need to account for the possibility that a [[:guard_behaviour#stationary]] [[:guard]] is watching the door, even if you [[:peeking|peek]] through it and listen for [[:guard_behaviour#patrolling|patrols]]. Because of this, on [[:modes:Expert Plus]], you should avoid opening doors unless you are able to account for this possibility, even with a [[:peeking|peek]] through the door. As a result, if you **can** account for this possibility, it can often be better to open the door (from a diagonally adjacent tile) without [[:peeking]], [[:peeking|peek]] with the door open, then (if noticed) get to safety.
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