When firing up or down a vertically, walls no not behave as expected. Both aliens and xenonauts are sometimes able to fire between the bottom wall and a second-floor wall, and at least sometimes are able to fire downward through floors.   The line of fire depicted goes between the wall; the alien shown fired out the wall to the street outside and later fired down into the office it is standing on. Later I was able to fire, but not see up from that office through the floor; are aliens a