The base principle is simple you search a house looking for things that were different in the original (anomalies). In case you find such an anomaly, you report it by pressing a button, and afterwards you loop back into a new iteration of the house. When you report right 13 times, you win.

The games random nature leads to ever different runs.

There are 30 anomalies that might appear in the rooms. However, there may only be a maximum of one anomaly at one time. As such, the playthrough length may differ drastically from ca. 40-80 minutes for the first playthrough.

If you dare to enter the dark rooms of Monday the 14th, be assured that while you challenge your memory and luck, you will be observed.