I'm better known for being a variety streamer these days, but when I was first starting out I was an avid speedrunner, and the one game that had its claws buried into me for that was Sonic 3 & Knuckles.
I had a personal goal of hitting a time of under 1h20m to complete the whole game including collecting all the Emeralds, which in turn opened up the "true" final level Doomsday Zone, and I achieved that in April 2020. Not only that, I got to perform a run live at EGX on the UKSM Stage, which is by far the highlight of my streaming career!
These days I'm much more into casual content - believe me, speedrunning can become a slog once you start chasing times so if you're thinking about getting into it don't get too bogged down with leaderboards! - but I owe a debt of gratitude to where S3&K brought me along the way.
