I came just recently into this speedrunning community so maybe I can offer an outsiders perspective. I didn't search for a game that I could speedrun. I just bought Jazz Jackrabbit, a game that I fondly remember from my childhood and just loved playing it. As I got better I started to write down my times on a piece of paper and at some point I searched if other people had done so in the past so I could learn from them. I didn't do this because I wanted to hold any records (as soon as my latest run is confirmed I am 5th of 6 people in the Episode 1 run and I don't think that I will ever go beyond 4th Place, because I usually suck at most games). Maybe my mindset is different than that of more serious speedrunners, but I think that actively searching for a game that you could speedrun for weeks, months or even years is not the right approach for most "normal" people. Just keep playing games and if you find something that you really like you can think about transitioning into speedrunning. I am often bored even before I am halfway through a game and running anything but Jazz doesn't sound very appealing to me.