From here https://www.speedrun.com/gamerequestrules
"Game Request Rules
Request Processing Details
Game types such as rom hacks, mods, mobile games, webgames, gamejolt, itch.io, and steam games will be held to some level of scrutiny.
• The game should have a reasonable length such as 5 minutes or longer.
• The game should show that a reasonable level of effort has been put into development from a functionality standpoint.
• The game should have been played by a reasonably large number of people.
• The gameplay should show some potential for optimization through speedrunning.
• Fangames with common names that create confusion in the search bar may also be held to a higher standard. There are hundreds of generic Mario fangames."

So, speedrun.com doesn't want very unpopular games on it, but how do they know if a game is unpopular? And any idea when it's considsered popular enough?

I thought maybe they look on f.e youtube for speedruns of the game, and if they don't find anything they think it's unpopular?