Raising the Bar Uncorrected Proof is a pre-release version of the Prima Raising the Bar book that was not meant to be sold or distributed.

This version of book was meant for internal use only. It was to be checked and corrected to ensure that any misconceptions and errors by it's authors and supervisors were removed.

One copy of the book was offered for sale on Ebay in 2016 and was bought by a Half-Life fan. A scanned version was then released to the public.

This version of book is a paperback that is almost 100 pages thicker than the original. One notable difference is that it contains much more information about the first Half-Life and it's development. It also includes exclusive, never seen before concept art and other miscellaneous material from Half-life 2.