That's pretty much me with most (open world) games.

I always treated games as a different worlds to get immersed in and that's how I approach them to this day.
I'm also a weirdo who likes to makes games more difficult and realistic/tedious for myself which means stuff like limiting the amount of carried items, not using fast travel, acting like an actual part of the world, turning off the UI if possible and choosing fashion over min maxing.

I don't think I ever did any kind of "gimmick" challenges. Probably because it kind of contradicts with my usual way of play.
It is however always interesting to read up on them - it amazes me what some people come up with to spice up their playthrough.