For games that haven't been released yet they usually have someone, in this case, who was mod of the original game or if they are a series mod. They don't usually let random people submit the game before it's released.

As Sam said, SRC only allows mods of other games in a series to request upcoming games.

For now the mod team is a few of the current mods of LA/LADX, but if we're overwhelmed with verification we'll turn to the community for help. Historically this means the admins will talk privately about who they'd like, then bring it to the full community to make sure there's no issues. If you join our Discord and chat a bit, it can help your chances but I can't guarantee anyone for a pick.

@DemataPyroDemataPyro : -->what spicefather said. Be active in the community, in the discord, show that you are an active player of the game and that you care and have knowledge about the game, the speedrun, the glitches - then it should be absolutely no problem to include you within the mod-team.

If you have absolutely no reference towards the games that you request, I understand why the SRC-mod team doesn't accept those requests - it's just saver for them! --> to avoid trolls and stuff. And if there are mods, that are already "trusted" because they take care of other communitites and leaderboards, then ofc they go with them.