(This is not a Brawl suggestion, i want this to be selectable all the time.)
I think we know that a lot of long time SN players/fans want to return to the roots of the game, with possibly re-releasing old alphas or the beta for people to replay. However I feel that holo probably won't do this unless it's a special occasion, so I want to propose something that I think could actually get into the game. A new gamemode exclusive to Custom Game.
Classic
The map for this mode is the classic Map 1 at least before the summer camp update happened (no vents), I know its possible for this since the props in LE. (bonus points if Mayak and MITH is still possible)
Autorevive can be toggled off and on.
Ghost, Guest, Otto, and Quentin cannot be selected. (the game will automatically select another class for you)
Talents are disabled.
No automatically placed traps
Barricades can happen, with the return of bricked off doors (can be toggled off)
If possible, the UI will change to match the old one (if its not too hard) (i'd say the lighting would change too, but that might be a bit much)
All Neighbors will get the remote control that otto has, minus the sonar ability in it
All characters get brought back before their reworks so:
Bagger gets all 3/4 regular slots
Scout is limited to 10 ammo
Basically its a return to the old style of SN without having to reopen the alphas, who knows, maybe you'll still gain xp and coins by playing this mode. I know it'll make people happy.