From the Publisher:

Play as a team with your friends as survivors of a zombie invasion in the Old West, with an action twist! Zombies are played by the game itself, using simple rules and a deck of cards. Find weapons, kill zombies, and build up your survivors’ adrenaline to unlock their true potential. The more zombies you kill, the more of them are coming!

Undead Or Alive plays with rules from Zombicide, with dedicated features including Survivor class abilities (Brawler, Faithful, Gunslinger or Townsfolk), new Zombie spawn rules, a Gatling Gun, and even a train, among others! Pick from the 14 Survivors to build your posse and bring justice to your frontier town through 10 missions made using the modular map tiles.

The Kickstarter full steam bundle includes:

Zombicide: Undead or Alive - Kickstarter Bundle
Zombicide: Undead or Alive - Gears and Guns Expansion
Zombicide: Undead or Alive - Steampunk Extras
Zombicide: Undead or Alive - Running Wild Expansion
Zombicide: Undead or Alive - Sister Temperance Expansion
Zombicide: Undead or Alive - Deadstock: Abomination Expansion
Zombicide: Undead or Alive - Long Dead Walkers Expansion
Zombicide: Undead or Alive - Paolo Parente Special Guest Box
Zombicide: Undead or Alive - Abominape vs Crocosaur Expansion