Survival of the fittest includes three all new card decks for last night on earth as well as new game mechanics such as barricades and sewers and 4 new scenarios heroes can now find powerful unique items and survival tactics the two new decks for the heroes the zombies are more ferocious than ever with the all new grave weapons deck it also includes 4 counter sheets and some new cards for the hero and zombie decks this expansion can be seamlessly integrated into all existing scenarios this i