An anonymous reader writes "It appears Valve has begun another ARG (Alternate Reality Game) similar to the one that led up to the release of the original Portal game. A recent Portal update unlocked a new achievement which has uncovered various hidden images and sounds containing references to the Portal and Half-Life universe. Many believe this to be part of the run-up to the announcement of Portal 2 and/or the next installment of the Half-Life series. A thread on the Steam forums has already reached over 1 million views as people piece together the information. Another thread summarizes the information found so far. Based on clues from the ARG, some are speculating an announcement at the 2010 Game Developers Conference where Valve's co-founder Gabe Newell is to receive this year's Pioneer Award."