Simple topic, what are in your opinion some great games that don't require your full attention while playing, for example allowing you to multitask or just let your mind wander while playing without missing anything.

For me the first ones that come to mind are Pokémon and Hearthstone, though I haven't played the latter in a lot of years.

Animal Crossing seems like the poster child for this. Time passes, but in real-time.
All of the mainline games just let you chill and play at your own pace.

It took me a while to get good at it but once I was EA's Skate became a game like that for me. I could just kind of absent mindedly run the same line over and over again while listening to some music or talking to friends.

Vampire Survivors.

It's so elegantly simple yet so satisfying, perfect for chilling out and letting the dopamine flow.

I sencond this. It's a game that can go both ways, hyper focus or chill brainless Fun.

I triple this. Vampire Survivors, Deep Rock Galactic Survivor, Death Must Die, and other Bullet Heaven (Hell?) games. I honestly am not exactly sure what the genre is called.

Quadrupled Vampire Survivors and it's clones and Tetris once you get good your hands automatically play the game. 

Sea of Thieves is a good one. You can run around and do quests absentmindedly while chatting with friends.

I think the Cities: Skylines games fit pretty well in this category. Yes, sometimes there's incentives to plan, troubleshoot etc., but generally the games don't require your undivided attention. They're also really easy to start for even short sessions, and you can do even just little things.

I havent played Vampire Survivors but it sounds like I should