Kerbal Space Program is easily my comfort game. This game has been with me through thick and thin.
I started playing when I was fairly young, I always loved space as a kid and naturally I found out about Scott Manley in 2013-ish. In those days he could have been considered a KSP Youtuber. I got the game around 2015, either a few days before or after 1.0 came out, as a "belated birthday gift" from my parents. I had actually played the free demo before that but as with all demos they're limiting.
I was never good at it then, getting to orbit for little me was an achievement on it's own. It took me 2 years before I got my first Mun encounter even. But I loved it anyway. I then started to watch old Danny2462 videos, Matt Lowne vids, Hazard-ish, and even RSS youtubers (Remember Chris P. Bacon?). Those were my afternoons and evenings after coming home from school, play a bit of KSP and watch KSP vids.
The game stayed with me as I got older, I learnt how to mod the game (which is a liquid easy task but not so easy to a 10 year old using his mother's macbook), I learnt how to actually dock, rendezvous (which im still awful at), and visit different moons and planets. Looking back on old screenshots from these days everything looks so bare but back then seeing this low resolution textured ball flying towards the mun in an attempt to recreate some old Soviet lunar mission was so much fun for me.
As I also love history, and specifically space history, I got into recreating real missions and crafts as well as I could. Mods helped so much.
When I think of those days I remember being a kid, just fawning over some rocket engines, and I was happy.
These days I still play KSP, I still watch the videos (For the channels who still upload), and when I heard that becoming an aerospace engineer was unlikely for me due to dyscalculia, KSP helped me cope with that. KSP is actually what kept me aiming for that education, and I'm working on getting my exams in order to apply. The way I play it now would definitely give a younger me some form of aneurysm, RSS/RO running kOS scripts and principia, but I have fun anyway. Really it was the customizability of the game through mods that kept me interested in it.
Sorry for the only partially structured gushing and memories, it's hard to structure my thoughts on something like this. KSP has been with me for over 10 years, and I hope it will remain with me for another 10 (given my hardware situation that's not unlikely).