If you throw grenade to a square in front of the open door to a room what spaces are affected inside the room?
Is it just the first one in front of the door or the two spaces in diagonal?
If it lands Corridor side of the room it will destroy the open door impacting the corridor squares adjacent to it and the room square adjacent to the door and the ones either side of it.
If it lands in the room square it will destroy the open door impacting all the room squares adjacent to it and the corridor square adjacent to the door and those either side of it.
If the door was closed then In this case it would destroy the door but not impact the squares the other side of the door.
NOTE:- if you can throw into the square through the door you can normally throw beyond or to the side of it ,depending on LOS blocked by walls but LOS of thrown objects is not blocked by friend or foe, so you can avoid blowing the door up and avoid the corridor squares. This is handy if you then want to enter the room and close the door to block smell range.
Rules Page 13:-
Explosives such as the grenade have a 9 square area of effect, which means they can damage multiple targets at once. Explosives detonating on the quare directly in front of a door will automatically destroy the door and (if not already active) it will activate the room and trigger a room spawn. A grenade cannot be thrown if there is another hero in the blast area.
It wont blast through closed doors or through walls.
Other units (friend or foe) do not block line of sight when using grenades. You cannot move diagonally into a door (unless Skinny Perk) but you do have a LOS.