Is it possible for a user to add a game, or at least request for it to be added?
Silindi
Speedrun is one word, reeeeeeeeee
Also, https://www.speedrun.com/requestgame
But since it's part of a series you might not have to do that. Just talk to the series mods and see if they'll add it.
There's just one mod for the series, his contact information is on his profile page -> https://www.speedrun.com/user/aisforandis