@10se1ucgo mentioned in #26 the ability to set a game mode that just tells the client to turn off all of it's existing game mode logic. No scorekeeping, default entities, etc.
Of course, this requires replicating the existing gamemode features first to be useful, so it needs at least #3 to be useful for modes like arena and #11 to create more complex game modes.
@10se1ucgo mentioned in #26 the ability to set a game mode that just tells the client to turn off all of it's existing game mode logic. No scorekeeping, default entities, etc.
Of course, this requires replicating the existing gamemode features first to be useful, so it needs at least #3 to be useful for modes like arena and #11 to create more complex game modes.