Experience

Experience is an in-game point system used to unlock new Characters. It is awarded on the death or level transition screen, and depends on the days survived. Each survived day adds 20 XP. Subsequent games add to the existing experience.

Unlockable characters

More than one character can be unlocked at once. For instance, if a player only has Wilson unlocked, but they earn enough experience to unlock Wendy, both Wendy AND Willow will be unlocked.