Champion Mode is an unlockable mode that allows players to indirectly interact with each other whilst playing the game. With Champion Mode enabled, the game becomes more challenging and adds an extra element of unpredictability.

Certain endings are only achievable whilst playing the game with Champion Mode enabled.

To unlock champion mode, you must collect 10 gold keys that are scattered throughout the dungeon, and use them to unlock the gold chest, once the final boss has been defeated. Opening the gold chest will present you with a choice, asking you how you wish others to remember you that dare to enter the dungeon. You must choose either "good", or "evil".

The choice you make will have an indirect effect on other players that are playing Champion Mode.
Your choice will be uploaded to the Steam leaderboard and used by other players that have Champion Mode enabled. A representation of your choice, known as a "Champion", along with your Steam username, will appear and walk along the tops of the dungeon walls, whilst a player makes their way through the dungeon, and will attempt to either help or hinder their progress depending on the choice you made.

Each time you successfully escape the dungeon, you will be presented with the gold chest again, allowing you to switch between good / evil, should you wish to.

To enable champion mode, enter the dungeon and hit the switch on the wall in the room directly after picking up the hand cannon (this will be the first room if you have quick start enabled).
To disable Champion Mode, simply hit the switch again.

In Champion Mode, all routes are hard.

Champions will walk along the tops of the dungeon walls, until you come within a close enough distance to them, at which point they will face you and become active. The specific actions of both Good and Evil Champions are as follows.

Good Champions, will spawn a blue Wisp directly in the room. The Wisp will pause for a second and then dart around the room erratically for a few seconds before it explodes, damaging anything within its explosion radius, except for the player. Attacking the Wisp before it explodes, will cause it to disappear and drop either a heart or treasure.

Similar to Good Champions, Evil Champions will also spawn a Wisp into the room, but this time it will be red, and upon exploding, will spawn zombies into the immediate vicinity of the explosion. Attacking a red Wisp will not cause it to drop anything, but it is in your best interest to, to avoid being overwhelmed with zombies.
Evil Champions may also spawn directly in the room to fight you, themselves.

Activating the Good Champions, whilst avoiding the Evil Champions, is the key to successfully escaping the dungeon in Champion Mode.