An historic battle concept has ALWAYS been proven by combat that he who controls the high ground, . . . controls the battle.
Secondly, in the typical construction of today's stick house, . . . there are at least 2, 2x4's at the door post of the doorway, . . . and 16 inches or less from it back toward the bg is another, and another, and another, etc. On the angle he has to shoot at you, . . . only a very lucky, lucky shot could get through the wall as he shoots up at you while ascending the stairway.
He presents a full body target, . . . you present half a face, half a shoulder, one hand, and a firearm, . . . raining lead down the stairway.
Only a danged fool, . . . a meth head, . . . or an Obama supporter is stupid enough to try to come up the stairway as I have pictured in the little drawing.
Tactically speaking: prone on the floor will get you killed, . . . you have to present your whole head and shoulders to get a firing picture.
Kneeling allows the bg to ascend half way or more before you have a full sight picture.
Standing, . . . behind one edge of the doorway, . . . you are behind reasonable cover, mostly concealed, and offer a very little target to someone below shooting up through the ceiling.
Retreating into a bedroom, . . . gives the total advantage to the bg, . . . he has some idea where you are, . . . you have no real idea where he is. He can initiate the fight from concealment, . . . slicing the pie into your room, . . . you can only hold your breath and hope you don't have a heart attack waiting for him to come in.
Take the high ground, . . . hold the high ground, . . . defend from the high ground, . . . it has worked for centuries, . . . it'll work in your house.
May God bless,
If you can breathe, . . . thank God!
If you can read, . . . thank a teacher!
If you are reading this in English, . . . thank a Veteran!