How does enemy door breaching work? [closed]

Question

Intro

During one mission where I was supposed to free a captured agent, I attracted the attention of a captain guard in the next room by opening the door in his vision, then quickly closing it again. Thinking that I was going to be clever, I had my agent place a shock trap on the door, and had her wait right behind it for the captain to walk right into my trap.

I was unpleasantly surprised then, when the captain walked right up to the closed door, announced that he was going to breach(!) it, and then completely blew the door up right in my agent's face, knocking her out for a couple of turns! The breach action seemed to disable the shock trap too, so that the captain guard was completely unaffected.

Questions

1. How does enemy door breaching work in Invisible Inc? I know that if an agent is standing behind a breached door, then they'll be knocked out for a certain number of turns (two turns?), but what if they're just standing 1 tile to the side of a breached door?
2. Does breaching a door always disable any traps placed on the door, like a shock trap?
3. Which enemies are able to breach doors? I know for sure captain-type guards are able to, but are there others?
4. When do enemies breach closed doors? When they're just suspicious (yellow question mark), or only when they're alerted and actively hunting you (red exclamation point)?

Answer 1

This comes down to the differences in guard behaviour when in "investigating" and "hunting" modes.

A guard who is investigating with a yellow question mark above their head will open the door normally. If they are actively hunting with a red exclamation mark above their head then they will breach the door. This is where they kick in the door which will KO anyone standing immediately to the side.

For this reason it is advisable to stand your agents to one side of the door, this also allows them to walk through the door before you KO them so you pull them into cover.

Answer 2

Regular Security Guards

So I just played a mission where a regular guard (not a captain) used a "Door Slam" which seems to work like a breach. Just like with a breach, the guard ended up knocking out an agent who was hiding behind the door for 1 turn.

The guard was alerted and hunting at the time. I don't know the exact specifics of the conditions under which a guard will use Door Slam however.

Akuma Drones

After hacking an Akuma drone, I discovered that it also has a "Break Door" ability, which costs 1 AP, though I'm not exactly sure what the ability can do besides "breaking" doors.

Answer 3

When are doors breached?

Human guards breach doors only when all of these criteria are met:

1. The guard is alerted (has a red exclamation point)
2. The door is closed
3. Moving through the door is the last step they have to take to reach their interest point

Notably, this means alerted guards do not break down doors that they're just passing through: they leave those doors open behind them and keep moving.

The reason for this is to avoid players exploiting doors to keep guards busy indefinitely. If guards didn't kick in doors, you could just hide forever on the other side of a door, and every time a guard opened it you could close it in their face and be safe for another turn. Remembering that may help you remember the conditions for guards kicking in door.

What happens when a door is breached?

Breaching a door doesn't disable traps: it activates them. So if a guard kicks in a door with a shock trap, the guard is KOed as if they'd opened it.

Breaching a door KOs any agent (or guard!) on the other side of the door for a couple turns. This includes only the tile directly adjacent to the door, not any tiles beyond it or off to the side.

Breaching a door leaves it broken for the rest of the mission. It cannot be closed again, and behaves as if left open.

Who breaches doors?

All human guards, but not human civilians, breach doors. Most drones do not breach doors. Akuma drones are special. Not only can they breach doors, but they do so anytime they pass through a closed door while alerted, instead of opening the door normally.