To gain access to The Basement, the player must have unlocked the Vault of Secrets and complete The Challenge. Upon beating the level, the Keymaster will claim he has an award for the player and prompts them to access The Basement.
The basement has a dark purple background with a locked cage, an animated torch on the left, 3 locks with blue, green, and orange keyholes, and a chest at the bottom-right corner. Once the player unlocks the chest given as a reward by The Gatekeeper, a pair of green glowing eyes appears inside the locked cage, revealing a monster that was locked inside the cage by RobTop; the creature requests that the player frees them in exchange for a reward. Selecting a lock will make the creature give a hint on how to get the key.
- The green key is part of a reward of the first golden chest inside the Treasure Room, which is unlocked once 50 Chests are opened.
- The orange key is gained once the player opens the chest inside the Chamber of Time.
- The blue key is received as a reward once the player beats the "Chaos Gauntlet" inside the Gauntlets.