This is a list of downloadable content avaliable for In Decay.
- Main article: In Decay/Relapse
Relapse is the only main story add-on available for the game. It follows a series of dream sequences imagined by protagonist Alex Walker and is considered the part of the series where we first see Alex turning into a darker, more indignant character. It is heavily focused on symbolism, torturing George with surreal imagery inspired and taken from the events in Felsborough.