"... fixed fortifications. Monuments to the stupidity of man. Mountains and Rivers can be overcome, anything built by man can be overcome." from the movie Patton
No offense Ohio, but if you spend your time trying to "harden" your house where do you stop?? Best strategy, harden the house to the degree that it negatively impacts the mobility of the attackers while maximizes your defensive tactics.
Keep your mobility:
I have a duty belt with gear (flashlight, reloads, radio / cell phone pouch) and my grab and go bag by my bed. Why? Fire, robbery, midnight phone call for any number of emergencies and I am good to go. I have a brace on the bedroom door. I have an iron gate over my front door, a heavy constructed and braced sliding rear door and a very good alarm system set at night full perimeter alerts and motion senors on. I have motion lights outside as well as some other tricks.
My house is a harder target than the neighbors house. Supposing that they do come here, I have the alarm system which defeats their surprise. I have a Boxer dog and a cat, the cat is a better early warning system believe it or not. The hallway to my bedroom is deadly choke point for attackers whether they use windows or not. The motion lights in the back give me an idea if we still have a line of retreat if they overrun us.
This isn't home defense, it is war and mobility is key. You have to minimize the enemy mobility, force them into kill zones to halt forward progress and maintain a reasonable avenue of escape to regroup and start the process over again. Done correctly, the enemy will either retreat or deplete their supply of man power. That is a victory, but the war goes on....