My autistic ds wasn’t keen on board games either but he liked to be the banker in monopoly, or the quizmaster. Sometimes we invented a judge role for him in other games.
We had some success with cooperative games, although we found it better to eliminate the countdown clock if there was one. Parallel play was always good - creative lego building together (not building a set though - he preferred to do that himself) and video games like Minecraft.
Our best discovery though has been D&D and I wish I’d found it sooner - because it’s story based, even when a dice roll goes against at you, it adds to the fun. There’s no win/lose tension and it’s cooperative instead of competitive.
But to get back to Christmas specifically, we start the day with Santa’s gifts even though they’re long past that now. We have a special breakfast - I set the table for it the night before. Because ds doesn’t enjoy his food changing, I put a bit more effort into the table setting, using special dishes, etc. Everyone else gets something a bit different to eat but it can vary year on year.
I used to love going to church but we don’t do that anymore. It was a great way to fill an hour, get a walk, see some familiar faces.
I always tried to get the dc something to keep them busy. Ds was easy - a big Lego set, Dd a bit trickier. But she’d help out with dinner prep and enjoy setting the table too. We have a big kitchen island, and ds can build his Lego while I’m cooking, and we all chat away.
Just before dinner we open gifts - this is separate from Santa, where we exchange gifts, and take a bit of time over it, taking turns, talking about the gifts. But it also meant that when the novelty had worn off the morning gifts, they had something they were eager to play with/read after dinner so that the adults could eat in peace and have second and third helpings. And maybe even a little snooze.
After dinner, we all move into the living room, where dh has a fire going, and it’s all cosy.
Eventually when I stand up again it’s time to help clear up the dishes, so it’s amazing how long everyone can play quietly together and not disturb me
Then we all play some sort of game, or cuddle, or read. At some point we have leftovers or dessert depending on who wants what.
Some years we have visitors but the structure of the day is the same. The years that we’ve been by ourselves are the best ones.