I have a lot of fond memories going over to my cousins going into splitscreen in a creative world to build or do literally anything we wanted; it was such an awesome experience making ice rinks and hotels and monster museums and door mazes, etc.
We'd have a lot of fun swapping (the two) controllers around and letting everyone have a go. They did eventually lose a controller which brought the experience down a bit, since it was only one person at a time then, and more people overtime seemed less interested in playing. But the good times were still there.

Undertale Yellow has got my feelings all mixed up now I've completed it. I so desperately want to rate it 4 stars because on the one hand it has a beautiful story (I went for pacifist) with strong, emotion filled characters - that had me genuinely in tears as the credits rolled, including a twist villain and new settings that definitely add to the worldbuilding and creative style of the original while being (very) faithful and creative with new concepts to differentiate itself, but on the other its creativity and gimmicks in combat have led to increasingly frustrating start overs.
I can't count the times this game made me want to slam my head into a wall because I wanted to continue with the story until I fumbled at the final boss and decided enough was enough and watched someone else beat the last 45 minutes of the game which I wouldn't have lasted even if I tried my hardest. The sheer amount of undodgeable attacks that do not care about being fair is uncountable and make me wish there was some extra polish because even regular encounters took a chunk of health out of me for that reason. One time I was close to a save point but lost to a regular enemy and had to restart and entire section all over again to reach it again.
Its a brilliant fan game, one of the best I've played, but my god do the fights need to chill. I probably won't be playing this again due to the frustrations of the battles but I might watch someone do the other routes.

I haven't played a lot of this game, but what I have played was some of the best fun I've had interacting with strangers in a call-like format ever. Playing as either your favourite characters or ones you made yourself is incredible and everyone I met that day was super friendly and I feel like this helped me get over my social anxiety and become more outgoing to people I'd only just met.
I tried to pick this up this again after a few years and getting my own pc rather than playing at a friend's but I had horrible anxiety that I wouldn't be accepted as a trans woman made me end up uninstalling it soon after (as well as my pc at the time handling it so poorly) though maybe I will give it another go in future, that first experience was enough of a driving force to try again.