Now before you get too excited, we have seen various references to Half-Life 3 made in the past, but so far none of them have actually provided any clues as to what the game could be about, or if it even exists. For all we know, it could just be Valve’s way of trolling gamers since they know how much they want Half-Life 3 to be real.
In fact this hl3.txt file isn’t as exciting as we were led to believe. According to some who have explored its content, basically it seems to be a file containing old definitions found in Source 1 that have been ported over to Source 2 with some minor changes. It has also been suggested that based on its contents that it could be definitions brought over from Half-Life 2 and Left 4 Dead.
In any case we could be reading too much into nothing. After all apart from conspiracy theories, there hasn’t been any hard evidence or rumors to suggest that Half-Life 3 is being worked on or close to being announced. However if you’d like to comb through the hl3.txt file, head on over to GitHub for the details.