This page is for doors mechanics that are present during real time gameplay.
Early Resident Evil titles
In the earliest Resident Evil games until Resident Evil CODE:Veronica, doors, staircases, elevators, and trapdoors have a special "loading screen" animation upon interacting with them. Each of them separates the rooms, while preventing some enemies from entering.
Resident Evil (Remake)
Similar to the above section with the added scare factor that some enemies (e.g. Hunters, Crimson Heads) can open doors to reach the player, catching many first time players off-guard.
Resident Evil 4 to Resident Evil 6 era
Tapping once on the Action button opens the door slowly while tapping twice on the Action button sees the player character kick or fling the door open rapidly. This can throw back or stun enemies that are behind said door, leaving them open to melee attacks. A small amount of damage is inflicted on enemies.
Resident Evil 7: Biohazard
In Resident Evil 7: Biohazard, pressing the Action button once will half open a door, pressing it again will fully open it, other wise walking into a half open door will open it. Moving backwards into a closed door will also open it. Moving backwards and pressing the Action will close a fully open door to closed, and a halfway open door to closed.
Enemies can not detect the player past doors that are half open. Most Molded can not open most doors that are fully closed.
The exception to this is Marguerite Baker who can and will detect the player through half open doors, and the bugs she then sends can travel through them.
Resident Evil 2 (2019)
In the Resident Evil 2 remake, doors no longer behave the same as the earlier titles. Like in Resident Evil 7: Biohazard, the players can half open a door if they slowly approach it. They can simply fully open by walking towards it or press the interact button. However, the player cannot walk backwards into closed doors to open them. Also, if the camera and the player aren't facing in the direction of the door, the door will not open.
Zombies in Resident Evil 2 are also capable of opening doors; they will recklessly slam the door until it's opened. The time it takes for zombies to slam open doors varies. Approaching a door that is being opened by a zombie will cause the player character to be stumbled. The player can also use this to their advantage by running past the zombie at the right moment right after the zombie opens the door.