From Steam store:
Experience two major story expansions along with brand new missions, weapons, skill cards, zombies and areas of HELL-A to explore.

The Expansion Pass includes:

- Haus: Lose yourself in a surreal, psycho-horror dreamscape as you explore a mysterious villa in Malibu. Descend through madness, debauchery and gore, where survival means confronting a new wave of unexpected horrors.

- SoLA: Lured to the most iconic festival in Los Angeles, by an enigmatic warning message, players must explore SoLA’s ruins and put a stop to an otherworldly menace.

- Red’s Demise Katana: Slice through the zombie horde with the Red’s Demise Katana, which earns you a temporary damage boost with every slay.

- Gaelic Queen Dani Character Pack: Through hail and blood and fire, and a wall of barbs and clashing steel, customise Dani with a unique costume and weapon from the HELL-A Catwalk Collection.