What's super fascinating is, I also have a hugely difficult time starting something likely due to ADHD. The addiction to novelty/stimuli and the inability to start things feel deeply linked for me, while you've got one and not the other. Unfortunately, this leaves me deeply unhappy, because one directly blocks the other. I'm desperate for new experiences but I lack the energy to do anything other than talk about old ones on internet forums.
People are funny.
I can relate to this actually. I require novelty in the sense that, if there isn't enough going on in a game that I can't keep getting more out of it every time I play it, I tend to write it off. Same with music or writing, if it stops "working", it's not good enough. Which doesn't create insane standards, surprisingly, but probably makes it harder for me to enjoy things than most people.
It's why, for instance, I've never been a fan of the rocket barrel levels in Retro's Donkey Kong games. They progress at a 100% set speed and all you can do is press one button to go up and release it to fall, so after you've fully completed them once, you've hit the skill ceiling and it's hard to get engaged with them. There's no meaningful variation in how you play them. I think I tend to obsess over platformers because at the heart of the genre is making the simple act of moving the character engaging. So that's constant stimulation you aren't getting from games where you just walk around.
Similarly, I like games like Panel de Pon and Puyo Puyo for providing this instant hit of intense action that will be different every time and that I will never even come close to hitting the peak of. Even that's not enough on its own, I pick those out specifically because they have characters and music and a setting, whereas I have more trouble caring about Tetris or Lumines (which has been sitting in my Steam library unplayed for who knows how long actually, I really should give it a go myself to see if I even enjoy it, but that blank futuristic aesthetic doesn't really grab me...) I love fighting games in concept for similar reasons, even though I rarely play them myself since I've never been much for multiplayer games. And I tend to stick with Touhou over other shmups because sure, they all provide a billion explosions and mind-bending rainbows of death to weave through, but this one has characters instead of blank spaceships, and the kappa's bullets move like waves and that's neat.
The only non-action genre I'm really interested in is RPGs, and to bring this back slightly adjacent to the thread topic, Paper Mario is one of my favorites because it minimizes the "watching numbers go up" side of the genre and focuses almost entirely on strategy with the badge system. While my body completely rejects the absurdly glacial pacing of non-Fire Emblem SRPGs, in general the impact of strategy has an enormous influence on how much I enjoy an RPG. I liked Ikenfell a lot more than most people, even though I thought the writing was poor and they wasted the setting, because I got really into the combat system that most people bounced off of very early. Every single battle was engaging and meaningfully different, which was huge. (It's basically like a Mario RPG on a grid ala Trails, but way harder.)
