Interface-wise, right now, when the player presses the space bar, any door within 1 meter of his bounding box in any direction is opened if its closed, and vice-versa. Later on, we will add keys and other conditions so you can't just get through any door.
It seems very simple, but it is very cool to watch the lighting & shadowing change when the door opens or closes. Physically, the doors are set to be 'kinematic' objects, in that they can push other things out of the way, but they don't receive any forces or impulses. This way they can't be blocked by objects in the way. If there is a barrel or boulder in the path of a closing door, it usually will naturally get pushed out of the way by the motion of the door. I have exaggerated the door's mass to magnify this effect, but it still occasionally happens that an object is between a flat area of the door and a flat area of the wall, such that it doesn't get pushed out of the way in time, and sort of becomes embedded in the door.
I might be able to detect this case and stop the door, or cause it to bounce back and open again, but there is the convenience factor of the doors just consistently working. Definitely a gameplay vs visual consistency issue. I am also considering detecting closing doors as a special case, and giving objects that interact with them an extra push normal to the closing direction.
Right now, I have implemented just left->right doors, but the other combinations won't be long in coming, so right->left and up->down, and n/s doors should be along shortly.
AI-wise, since I don't expect opening & closing doors to be an extremely frequent scenario, when a door finishes opening or closing, I will cancel the paths of all enemy characters to they can re-path, and then either break or re-create the navigation links that the door blocks.