The House
The house in Emily Wants to Play doesn’t get much of a backstory to it while you play. One thing you do learn is that it houses those three mysterious dolls that become Emily’s playmates. They are creepy and use every room and access point to their advantage.
Whatever the house was before the events that preceded your arrival, it is now a sort of tomb. One that collects the bodies and souls of those who enter its walls. This seems to most definitely be the case when you take a look at the artwork scattered throughout the house and one of the final recordings found in the basement. The recording says in the three demonic voices of the dolls:
“Don’t ever leave. We just want to play. We are one.”
The dolls want to have fun within the house, they just go to deadly measures in each of their games.