That's Not My Neighbor is a horror game incorporating elements of deduction, in which you take on the role of a security guard hired by the Doppelgänger Detection Department (DDD). Your task is to screen visitors arriving at an apartment building and determine whether they are genuine residents or dangerous doppelgängers. Doppelgangers are capable of disguising themselves as humans, but they often reveal unusual signs if you observe carefully enough.
Whenever someone appears at the entrance, you must ascertain who they are and the purpose of their visit. Check their identification documents and cross-reference the provided information against existing records. From the outset, you can easily verify details such as a visitor's name, apartment number, and physical appearance. If anything seems amiss, you can conduct further verification by asking a few targeted questions. If you are certain that an individual is a doppelgänger, use the telephone to report them to the DDD. Conversely, if you confirm that the person at the door is a legitimate resident or an authorized guest, you may grant them entry into the building.