So, for a little context my house has a basement with a few rooms. There's the laundry room, the main room, and a room in the back. Now, my brother (25M) put what was basically a second living room with the Xbox 360, PS2, and Wii in it, and a bedroom in the back room. When we moved in I (14M, around 6 at the time) wanted the basement living room to be a shared den type of space, but my brother declared the whole basement to be "his personal space" and barely ever lets anyone down there. Now keep in mind the room in the basement which he chose to sleep in is huge, bigger then my room and the master bedroom combined. Meanwhile I don't even have a bedroom to use. Because the room that is mine is directly above his if I make any sound he gets upset. And I don't even sleep in there, my bed's in my Mom's room.

Anyways, as the game consoles are down there, so were the games. And a good amount of those games were mine, either given to me as presents or I had bought. And because the basement was owned by him and the games and the game consoles were down there I was barely ever able to play them, like 3 times a year on average. Because of this I had to get a few consoles that I put in the upstairs living room that I have shared with him entirely. And a few times I've brought up to him that it's not fair that I let him use the stuff upstairs but he doesn't let me use the basement stuff and his response is always "Okay I'm sorry, I'll never use the PS4 or the Xbox One again" (this is just a little more context).

I bought a game for 360 that I thought would be backwards compatible with Xbox One but it wasn't. My brother let me play it downstairs and I was really hooked (It's arkham city btw, fire game) and so the next day I asked him if I could play it again to which he told me that I could but only under adult supervision so I needed to get out Mom to come down with me "In case I have a meltdown or something" something that literally hasn't happened since I was like 9. I was already pretty annoyed at that comment but I tried to brush it off at least for a little bit. I found my Mom and I asked her if she'd go downstairs with me so I could play it but she wasn't feeling good and I didn't want to drag her down there since it's cold in the basement and she'd clearly expressed to me that she doesn't exactly enjoy just sitting there and watching me play video games.

So I tried to talk my brother into just letting me go down there by myself. Y'know I'm not a little kid anymore, Mom isn't feeling good, etc, etc. He kept saying no and it ended up turning into a massive argument between everyone. And toward the end he basically said that I couldn't use it anymore. So I said "fuck it" and the next day I bought my own 360, and then today (or I guess yesterday technically since it's 4am lmao) I went down to the basement and I grabbed a couple of games that were mine. I got upstairs with them and he demanded that he looked through them. He looked through the few games I'd grabbed which were mine and found a game that he liked and he said was his.

Oh boy... I tried to tell him that it was mine and that my Dad (we're half siblings) got it for me, but he insisted that my Dad got it for him. My Mom sided with him in all of this. We argued for like... 30 seconds before he pulled the "YOU KNOW WHAT??? JUST TAKE IT!! I DONT WANT IT ANYMORE!!" card and ran to the basement. In the meantime I tried to call my cousin because I thought he might remember, but he didn't asnwer so I called my Dad to ask him which he confirmed it was mine and his story of what he remembered was eerily similar to what I did.

I told my Mom and she basically said, "You were just gonna call as many people as you wanted until you got the answer you wanted to hear." Which uhh... No? I called two people and 1 of them picked up and it was the man that bought the damn thing. Anyways, I planned on going to get the rest of my games and so I told my Mom about it and she called my brother to tell him/ask if it was okay, I guess. And he said that I could but she had to come down with me... For some reason...

Anyways so that's what I did. I went down there and I started grabbing the games that were mine, this time though I didn't just grab the games that were for 360, I grabbed the games that were mine for all the consoles. That's when this bro started yappin. One of the things he said was, "Oh, well if you're gonna do this then I guess I have to go upstairs and take the games for the PS4 that I bought."
And I said, "The PS4 is a shared device."
And he said, "So is the stuff down here."
And I said, "Yeah, except I actually let you use the PS4."

And then they tried to gaslight me into thinking that he never said the thing about me not being allowed to use the games downstairs. And he also started trying to give me stuff that I had given him as a birthday present. And then when I tried to say that it was a present he said "Well clearly that doesn't matter, does it?"
Me: "I Literally asked my Dad and he said it was mine."
My Mom: "Yes, I'm sure that your father remembers a game that he bought after 10 years."
Me: "You know what's funny about that? His memory matched mine."

Then a little bit after that my brother started trying to hand me stuff that my Dad had gotten him before I was born since it was "yours now and I don't want it anymore." or something. I think at one point I basically said "Why are you trying to make me feel bad for taking back what is literally mine?" and my Mom said "Why are you making such a big deal about silly video games"
Me: "Because they're mine. They're my property."
Mom: "Well when I left stuff at [blank]'s house and they told me not to worry about it I didn't mess with it anymore even though it was mine"
Me: "Well I'm not you."
Mom: "Maybe that's a good thing"

???????????????????????????????

Anyways, in this whole ordeal I feel like they're both being manipulative, my brother is infantilizing me, and I'm starting to think my Mom is favoring my Brother as well as being the type of person to let people walk all over her.

Although that aside I do still kinda have some internal conflict with this. What do you guys think, Am I the asshole?