1998 Half-Life
...
2004 Half-Life 2
2006 Half-Life 2: Episode One
2007 Half-Life 2: Episode Two
I see what you mean, now.
However, not only has Valve been doing many other things in the interim, there was also about six years between the original HL and HL2. It might be a little longer to wait.
However, I would also not be surprised if Valve were to wait for the SteamOS release, and then announce HL3 as a "flagship" SteamOS game. They already have dozens of such games that work, but not as many that will make people put down their COD, GTA V, etc and play with a SteamBox in their living room.
I doubt/hope it won't be true "flagship" title with Steambox/steamOS exclusivity. However, maybe they'll do a bundle similar to xbox where if you buy a steambox you get HL3 included? HL3 could definitely be Valve's game that makes the steam box a major player, similar to Halo for xbox. Valve feel free to hire me.
I see what you mean, now.
However, not only has Valve been doing many other things in the interim, there was also about six years between the original HL and HL2. It might be a little longer to wait.
However, I would also not be surprised if Valve were to wait for the SteamOS release, and then announce HL3 as a "flagship" SteamOS game. They already have dozens of such games that work, but not as many that will make people put down their COD, GTA V, etc and play with a SteamBox in their living room.