I really enjoy this game, so i hope you dont mind i write down som ideas i would like to see in this game:
1. Since the neighbors mention visitors, i would really spice things up if non-residents like relatives or delivery men wanted to go through, making to check them too if they are not doppelgangers.
2. You probably are planning on this, but i really want to see a story type game mode, letting you to know more about the neighbors personally through several days, cause im really interested to know more about these characters.
3. This is a stretch, but it would be cool to have an emergency gun which we can use in dire situations like a doppelganger trying to break in, or one of them holding a neighbor hostage.
4. I dont know if there exists more creatures in this games world other than doppelgangers, but it would be hilairious if a straight up friendly skeleton, or something similar, wanted to visit a neighbor and is not a threat.
These are just some silly ideas i had in mind but needless to say, im really excited to see what you are planning to add to this game!