Backrooms is a liminal maze with 100 percent map XP. Pack-a-Punch opens after you pick up eight pages, the same count used by the Slenderman-style objective. A counter tracks the pages. A video walkthrough shows all eight spots and ends on the machine after the last page.
Buy Juggernog before a long search. The Golden Knight wall buy, and the Golden Knight Mark II wall buy, are the map exclusives. SMGs fit the halls better than slow shotguns. Headphones help because the rooms repeat.
A secret Slenderman jumpscare can play while pages are collected. The written guide treats it as a scare, with zombies still the thing that downs you. Pages are shared in co-op if you split up.
After 8 of 8, Pack-a-Punch the Golden Knight or your box weapon for 5,000 points.
Juggernog on this map is documented across from the Vector wall buy. The older arc list places Backrooms in arc 3 with Chaos Canyon, Five, Iron Cafe, Kino, Octagonal Ascension, and Poolrooms.