Specific Door Types

When revealed through exploration, doors are always shown as the exact weapon type needed to open them. When revealed by a map room, doors may be shown differently, such as a non-descript door symbol. All specific door types become blue doors after being opened successfully the first time.

Door Symbol Categories

Color	Category	Description
Blue	Any Weapon	Anything can open. Also the general door symbol when not shown with specific types.
Gray	Locked	Unlockable only by meeting the unlock criteria. Often a boss kill, puzzle solve, or switch activation.
Red	Missile	Hit with Missile or Big Missile to open.
Green	Big Missile	Hit with Big Missile to open.
Yellow	Big Bomb	Hit with a Big Bomb to open.
White	Elemental	Hit with the matching elemental weapon. Always white, but look for symbol to see which one.