As with any rumor take everything you read here with a grain of salt. While I don't think the leak is fake (given that you can check yourself) it still doesn't mean that the games are coming, or if they are, coming any time soon. Halo 3 showed up in a similar leak a while back yet never appeared on PC.
With all of that said, a couple of people over at Neogaf complied a list of games they found by digging through Steam's help website. Most interesting of which are Final Fantasy X & X-2 as well as the sequel to the immensely popular (how do I even own this?) and amazing Bad Rats!
That was a joke by the way, do not under any circumstance submit your Steam account to the heinous villainy that is Bad Rats. I don't say this because the theme of the game is distasteful, rather because it is so buggy and unpolished it is practically unplayable. Funnily enough, if the sequel fixes up the physics engine I can actually see Bad Rats being fun and not just something you infest your Steam friends accounts with.
Besides the three games mentioned above there are a few others that are most likely coming, here's a list of those that still don't have a confirmed PC release:
Guilty Gear Xrd - a generally favorably received fighting game from the PS3/4.
Ty the Tasmanian Tiger Series - A bunch of colorful platformers from the PS2. With the fourth game already on Steam it makes sense the rest will make a transition from consoles to PC as well.
Danganronpa 1 & 2 - a pair of messed up but really interesting visual novels from the PS4 and Vita.
Everybody's Gone to the Rapture - a PS4 exclusive that focused on exploration and storytelling
And yes, I am aware that Half Life 3 was listed as well but references to Half Life 3 have been popping up in various parts of Steam for years now so until Gabe himself shouts out "Half Life 3 is finally coming" I'd suggest you don't get too excited about it.
That is it as far as the leaks are concerned. Once again, while I don't doubt many of these are coming to PC, take this rumor as what it is, a rumor.