I'm so sorry

This is why I always just setup games, explain victory conditions, and start playing a round as I explain the mechanics - I offer to reset after the first round but folks usually just want to play it out.
- explain victory conditions
  That is key. Then I add these things help you, these others are obstacles.
  
  It is infuriating to me how often people start explaining the rules without explaining what the actual goals are first. Like, what are we even doing here, start with that, m’kay?
  
  I've had bad experiences with not doing victory conditions upfront since they're sort of back-of-mind considerations I'll forget about them until I start shifting my build/position/strategy to pursue one. Making sure everyone knows the long term goals is important before decisions are made or else folks will feel disempowered in the flow of the game.
  
  It’s tough, cuz usually I sell people on the game by focusing on the fun mechanics of it, so it’s easy to go straight from mechanics to setup to first round, and have that awkward moment of “Wait, how do you win?”
- I'm getting into Battletech and it's so good for that. The basic game is pretty intuitive, as long as one person knows what to roll and when it's really easy for a new player to pick up. I'm growing my Inner Sphere collection so hopefully I can get all the folks I'm close to to give it a try - just lay out a bunch of Mechs with sheets ready, say "pick 4 and let's blow shit up" and have some fun.
  
  My first time playing battletech was just me and a friend of mine who hadn't played either, and we both have fairly severe adhd symptoms. Trying to figure out how to keep track of movement rolls was confusing to say the least but we eventually got it.
- I've explained hundreds of different games over the years and top-down is always the way to go:
  "This is the theme and how to win" ↓
  "These are the things you need to win and these are the things that will hinder you" ↓
  "This is how each round is structured so you can get/avoid those things".
  If you do it bottom-up then people ask, "Why would I want that?" or "What's that for?" and you're constantly replying, "I'll get to that".
  Practice rounds are one of my favorite ways to do it, but sadly my current group doesn't like them. Definitely the way to go if you can, though.--
  
  For some people that will work and it's absolutely the optimal way to explain it - but I think that much information (critically stares at himself constantly over explaining) can be overwhelming.

Dont worry it's real easy
- Middle aged man. Who has always wished I could play 40K. But my memory issues and adhd make it impossible on my own and I don’t know anyone to ask about it.
  
  Try battletech!
  
  Even in my country and out in nowhere they have game shops now where you can just go and you will meet enthusiastic people that will be thrilled that you want.

"I'll probably get it when we start playing, don't worry, haha!"

I love boardgames, but learning new ones (especially if you are playing a friend/family's game they are trying to teach you) is so bloody painful. I wish I knew ahead of time what the game will be so I can pre-learn the rules on my own.

My game night group asked me "Can you read glyphs?" I said "yuh". They said "And you play 4x and resource managers on PC?" I sead "yeah". They said "perfect, win conditions are... You'll go last to watch phase order"
I've never had games more succinctly and accurately taught than my current game night group does.
We taught someone magic the gathering in 20 minutes, they won! (We have a noob friendly format we've made which has the goal of eliminating metaplays through a shared 400 card library and an extensive banlist)
- Yeah, the best way to learn a new game is by doing it. Video games have stopped burying tutorials in booklets, because they realized players didn’t actually read anything. Instead, they use the game itself to teach you how to play, by presenting the relevant information as it becomes relevant.
  You don’t need to read rules about a mechanic that starts 3/4 of the way through the game until you’re at the 3/4 mark. In video games, that usually manifests as a “congrats, you got a new ability. Here’s a quick three or four sentences on how it works” pop up. If that info is presented up front (like in a board game rulebook) then you’ll have forgotten how it works by the time it is relevant.
- Knowing what to teach a new player is so important in games. They're not going to have fun if they're drowning in the deep end
  I have a Talrand commander deck specifically designed to teach new players. It is real simple to explain: you get creatures by casting spells, use those creatures to attack people. All the spells are low mana cost "do a small thing draw a card". There is utility everywhere worded simply and it's great for new players. Then to keep them engaged with a chance to win I threw in a couple things like coat of arms that can fire off a same turn win even against better decks
  I also collect ttrpgs and being able to teach relevant rules in an engaging way is required. I'd never be able to play half the games I own if people didn't like the learning process to try them out. With ttrpgs it's easier to be like "eh I don't like that we're glossing over that rule" than with board games though which can really smooth out the initial learning curve

Let's play a practice round
- Or “wait can I see the rules real quick?” and just skim through the bits my brain is missing.
  
  This. Your explanation made sense to you but glossed over the interplay of a few variables and nuances I need to fully grasp the intent. I need to see the instructions in context to get it.

I'm an adult now but I think I have ADHD, like this for example someone could be explaining something important to me but my mind is off in a dozen different places missing everything
- One of the main factors that made me decide to go get a diagnosis at 30 is I would ask a coworker a question and struggle, I mean REALLY struggle to stay focused just to hear the answer to the question I just asked them. Like, I asked them, wtf belrsin??? Sometimes corrections in sleep and diet can make a difference here and there, at least for me, but if you've tried everything and literally are suffering from it, go get checked. Because if you do, and get medicated, you'll feel like a god damn superhero. It is insane the difference it makes when you've been dealing with your symptoms for decades.

When I first started dating my current bf, he brought out Kingdom Builder. We played, it was fun, he got excited that he found a game I enjoyed. Excited enough that he went ahead and bought the rest of the expansions.
Next time we got together to play games, I got REALLY confused and struggled because the rules changed. A big lesson was learned in that moment lol. I struggled overall for a while because everytime we played a game and I felt like I was just starting to get it, some aspect of the game would change and I felt like I was starting over again. In time we've found some compromises that work for us though. Legacy games FTW!

the only way to learn a game is to play it imho, at least it’s the only way i can lock in and actually keep track of understanding it

I just ask what I do on my turn.

"For the love of god, please write it down so I can review the rules.. Yes, including the house rules... Not only because I don't want you to change up the rules on me suddenly, it's because I'd had forgotten what are the rules and what aren't BS made up during.."
That's me if someone plays a new board game with me

- I think this might be why I got into competitive online games; it seems like one off the few ways to get everybody at least thinking about it in the same way

I am the best at not understanding the game but winning the game anyway.

Dont worry. I'll get after a couple of rounds...
- Let the normal people grasp it first then let me watch them play. I'll join in next game.
- My usual strategy. Have to play hands on before I get it at all.

And I keep zoning out in the exact same place too...

Snorky: I, King Snorky, hereby banish all humans to the sea!
Moe: I tuned out. Where are we going?
Simpsons

Well, I am also sorry I explain it for the fifth time during the same evening while clearly nobody asked for that and nobody except me plays board games anyways.

I literally record every work conversation so I can go back to it when I zone out.
I even record my personal conversations. After Samsung added AI transcriptions, I have become a better person.

Errrgh it took me three attempts to read that

I wonder if it's really ADHD, or it is just that it is human nature to learn better by doing the task themselves, instead of simply listening. The expression "practice makes perfect" is indeed true. The connections between brain cells thicken and strengthen the more you repeat a task.