Lost Alpha is a free addon for S.T.A.L.K.E.R. - Shadow of Chernobyl.
Here is a short werk movie about Lost Alpha, how it all started back in early 2008 :)
This video shows development images from 2008 to late 2009 and early 2010. We did not want to include 2010-11 screens, since levels changed a lot, and we wanted to avoid spoilers! You will find all the stuff sorted to days, months, years and user names in our extra dvd, bundled with Lost Alpha! (just a simple .iso format which will be released with lost alpha)