I played a few variants when I was a kid and into chess and designing games. Our third-grade class got into chess for a while and IIRC a popular variant was to ignore check and checkmate.
It’s cool there are so many variants listed. I would’ve loved that when I was more into chess, though it would also take hoarding several sets to have enough pieces for some of those.
When I got Chess for the Atari 2600, I and some of my friends tried some variants just by using the editor to have different unit matchups. My cousin just liked giving himself an army of Queens and torturing the computer opponent without having to think much.
I used to like playing against the computer giving myself a head start in setting up my pieces in a good position.
My dad and grandpa used to like to solve chess problems, especially when they got their first computer chess sets, to see if they could solve them. My dad and a friend also used to play by mail, and both ended up using their chess computers for the moves, (and at the first, they were both doing that and not telling each other.)