In FTL, higher levels of the door subsystem provides three purposes (in addition to interacting with an event or two):
- Higher levels of the door subsystem give more durability to the subsystem, making it harder to destroy (which causes you to lose control over your doors.)
- Higher levels of the door subsystem make doors require more melee attacks to force open by intruders; level one doors require no such force.
- Higher levels of the door subsystem slow the spread of fire from one room to another, when there is a shut door(s) connecting them.
This question is about that third point. Specifically:
- How quickly does fire spread from a room filled with fire to another if there is a level one door between these rooms?
- How about a level two/three/four door? (Level four doors are attainable in the Advanced Edition with someone manning a level 3 door subsystem.)
- Does it matter how large the room is that is on fire?