Doors:
Different doors may prevent you from continuing your path. They have to be unlocked in different ways.
Wooden doors:
These doors can be opened with switches. Some switches can open and close doors whenever wanted, other switches can only temporarily open doors.
Regular switches:
These switches open and close doors whenever you pull them.
Temporary switch:
This switch will temporarily open a door, you will need to hurry.
Stone doors:
These doors can only be opened with stone pressure pads. You need to stand on them, have a monster stand on them or drop a stone or explosive crate on it.
Pressure pads:
This pressure pad already has a stone on it, thus keeping the door opened.