There is no such thing. Steam is nothing more than a distributor (such as fileplanet) with a client that keeps all of your games together and does a few other neat things. Other than that, the games you play THROUGH steam have no connection to steam at all. Dragon Age is made by Bioware, Fallout 3 is made by Bethesda etc. etc. Now if you are talking about Left 4 Dead, Half Life, Portal etc, those are Valve games. Valve just happens to also be the company that made Steam. Oh and on that note, STEAM games are not being ported to mac. STEAM dosent make games. VALVE games are being ported to mac as well as the STEAM client.