Steam is one of the two digital distribution platforms required to play the most recent versions of Project Zomboid, with the alternative being GOG.com.
The Indie Stone first posted Project Zomboid as a Steam Greenlight candidate on the 31st of August, 2012. After overwhelmingly positive feedback from their community - in which they had already formed due to their previous releases on Desura - Project Zomboid was greenlit and released on Steam with version 220.127.116.11 build 11. With their steam release, The Indie Stone were worried as their game would not appear in 'New Releases', relying largely on the community's "word of mouth". The release on steam saw a price increase from £4.99/$7.49 to £9.99/$15.99.
'I Will Back Up My Save' branch
I Will Back Up My Save or 'iwillbackupmysave' as it is referred to in Steam, often abbreviated to IWBUMS, is a beta branch exclusive to steam users. The 'iwillbackupmysave' branch of Project Zomboid is an unstable experimental build, available for any steam users to opt into. On this branch, they will have access to new features along with new bugs. The purpose of this branch is to aid the dev team in finding any remaining issues before it is released to everyone on the main branch. Details on how to opt into this and other beta branches can be found on the forums.
The Steam version of Project Zomboid comes with a collection of trading cards for fans to collect. There are a total of six trading cards, each with a much rarer foil variant, that once collected, can be used to craft a badge that can be displayed on their profile page, along with granting XP towards their Steam level. There are a total of five badges and one foil badge to be earned, rewarding the user with 100 XP for level 1 and increasing by 100 with each badge level. Each badge references how they died, with the foil badge as an exception, the title reads: "Ain't Dead Yet".