Hello. I have some ideas.
A reverse mode, where you are a doppelganger and can't let humans in. The humans are disguised D.D.D employees.
An indicator how far we are in, like a clock on the wall or a sky that goes from morning to evening.
People going out and getting added to the list.
Ability to add checkmarks to the llist.
A list of all seen doppelgangers. Like a bestiary.
The game is fun. Can't wait what you are going to do next.