The Hidden Key is a 'monster drop' that was introduced during the Ratboy's Nightmare Update. It is one of the many collectibles that are needed by the players in order to complete the entries of the Itempedia of the Nightmare. The Hidden Key can be obtained from the boss found in The Road or at the End of the Road, known as the Democan.
In appearance, the Hidden Key appears to be a twisted metal key tainted by nightmarish energies. Other than that, not much can be said about its looks.
The Hidden Key is mainly used to unlock doors sealed with the keylocks that can only be opened by the Hidden Key. These keylocks are made out of the same materials of the Hidden Key, being black and obsidian-like.
After a player had unlocked and entered a hidden key-locked door, they may explore The Lost to fight the mobs that inhabit the zone.
- Unlike the other keys (Ancient, Mansion, Theatre), it cannot be obtained from the Pig if the players had lost or dropped it.
- Before the developers applied a small patch a few days after the release of the Ratboy's Nightmare Update, The Cricket could drop the Hidden Key, however, this was later revealed to be mixed up with the drop table of the Democan.
- The Hidden Key has a 24% chance of dropping from the Democan.