S.T.A.L.K.E.R. Shadow of Chernobyl came out for PC back in 2007, but a long development time with several delays and problems meant that some content was cut from the final release. Now a group of fans the Lost Alpha mod, six years in the making, which restores those cut levels and adds new features and improvements.
"The project first started out as a modification to add back the cut levels which all Stalker fans knew of," reads the announcement post on Mod DB. "After a while, it became more than just a modification, it became our dream game, how we saw S.T.A.L.K.E.R. We hope to give you the same feeling when you first played S.T.A.L.K.E.R. A new chapter with familiar elements without which S.T.A.L.K.E.R. would not be the game we all grew to love. Lost Alpha was a labour of love. We are passionate about it and we hope you all will enjoy it as much as we enjoyed creating it!"
You can download the mod via Torrent or in four executable parts. The mod team are promising to continue working on improving the project.