Analyze and explain what makes this Reddit true horror story so creepy:

I've seen some pretty wild stuff in my life but most of it is explainable, the one event that comes to mind was witnessed by my dad, brother and myself and it's a 2 part encounter but I still consider it 1 event.

(This is a bit long and I apologize but I feel it might be worth the read)

It was around 1998, my family and I had just moved into an old clap board house on the edge of town. It had a huge back yard with a 6 foot wooden privacy fence on one side and a metal chain link fence about 4.5 feet high around the other 3 sides of the yard. Neighbors on one side (the privacy fence side) a small grass alley that ran behind the back with a street light and then another yard etc. Our bedroom was an old converted sunroom on the back of the house that faces the back yard. It had floor to ceiling windows all along the back wall looking into the back yard. We didn't have many options as to where to place our beds so my headboard was against the windows and my brother's bed was about 8 feet away with his head board against the opposite wall with the foot of the bed facing the windows.

One night we were up pretty late, I was in my bed and he was in his just talking about random things when suddenly he got quiet. I figured he fell asleep but then I heard him whispering in a shaky breath, so I'm like "What?" And I hear him whisper again. So again I'm like "speak up I can't hear you" and he goes "Don't Move! And be quiet!" In a forced whisper but I, thinking he's messing with me and like "Bitch, why?" And I'm looking at him and mind you, my head is to the windows and he's pointing into the backyard behind my bed. So quickly sit up and turn around and see this HUGE dog head staring almost nose to glass through the window right behind my bed. I'm almost nose to nose with this thing, just a single pane of glass and about 10 inches of empty air separate me for this thing. Now when I say I screamed, I mean I screamed! Not my proudest moment but hey I was like 10 years old. Well anyways the thing quickly ducked under the window and then ran to the side of the yard and jumped the 4.5 ft chain link fence and bolted off into the darkness. My dad came running into the room with our mom right on his heels. We were able to get out that something was looking through our window. So dad ran back to his room and grabbed his shotgun and then headed out the side door of the house and into the back yard.

Unfortunately (or fortunately idk) he didn't find anything, wrote it off as I had a nightmare and my brother wouldn't admit to seeing anything so I took the blame and was told to quit messing around go back to bed typical parent response etc.. Well later that night (maybe an hour or so) after I begged my parents to let me sleep in the living room because leaving the house wasn't an option and still being refused, I was made to sleep in my room. So again my brother and I are in our room with these floor to ceiling windows, we are just completely rattled. We are both huddled in his bed staring out the windows when we see this thing come walking along the chain link fence on all fours and the fence only comes up to its mid shoulder so this thing is HUGE. It sniffs the ground, does a few circles and then hops the fence into the backyard like it's nothing. It walks over to the window and again gets nose to the glass like it's trying to see in. We are panicking the whole time, well my brother is like "Fuck, This" and soon as he steps off the bed we hear this loud Bang and there is a flash of light. The thing at the windows gets knocked sideways and without even missing a beat it turns and runs across the full length of backyard jumps the back chain link fence, it cleared the fence the alleyway and then landed in the back neighbors yard. This is easily a 15-20 foot jump minimum clearing their fence like it was nothing and was gone at a dead run, up beside that house and off into the darkness on the other side. My dad comes tearing around the side of the house with his shotgun in hand and makes a mad dash for the side door and slams it shut behind him. He is screaming and hollering we gotta go, we pack up and head to a hotel that night. My mom absolutely refused to believe we saw what we said we saw and we only lived there for about 6 months. It rattled my dad so much he didn't even want to come back, he told my mom that we were just gonna move that next day but she wouldn't allow it.

After about 6 months she conceded and we moved. Mind you this is in the Coastal plains region of Texas we have no large wild canines here. We have stray dogs and coyotes but nothing that would even remotely touch on how big this thing was. My dad swears he shot that thing with a slug from about 15 feet away with his 12 gauge shot gun right underneath its left arm hitting it in the ribs where its vital organs are and nothing it just ran off.

He said the thing that freaked him out the most was that when he saw the thing jump the fence it walked towards our window crouched but still on its hind legs. It wasn't walking on all fours and then when it got to our window it stood up straighter and he could tell that while it looked like a dog it's body was shaped wrong he said it looked like a really stocky  person wearing a dog suit but he could tell it wasn't a suit. Also that when it was walking in circles sniffing the ground before coming into our yard the second time it wasn't actually sniffing the ground like for a scent, it was staring at our window with it's face to the ground like it was acting like it was sniffing the ground almost as if it was playing a part to see if anyone would notice it. He said he's had dogs his whole life and everything about what it was doing was wrong.

Awhile later I asked my dad why he was in the back yard if he thought I was having a nightmare and he told me my brother is the one that gave it away. He said with how panicked I looked, that my brother was almost white as a sheet and wouldn't take his eyes off the window. He said "your brother has never looked so scared and never been one with just making stuff up." So after going back to his room with my mom as he was laying there thinking about it he decided that if my brother was a white as he was then we had to have seen something. So he grabbed his gun in case he had to scare some creeper out of our yard and figured he was gonna go through the garage and out by the far side of the house and sneak to the corner to see if someone was peeking in our windows or if someone was actually messing with us. He never actually thought we saw a huge Dog looking thing just that maybe with it being dark outside and us being kids with over active imaginations maybe we just mistook someone as something. But when he saw that thing come up the side fence and with the street light in the back alley lighting up the back yard he saw it and it freaked him out, he was gonna creep back inside until it went up to our window and he said as it stood up he just got this instant feeling of just dread like something was gonna happen to us.