Little is known about Valve founders Gabe Newell and Mike Harrington, but they are undoubtedly smart fellows. Both worked for lengthy periods at Microsoft, becoming some of the "Microsoft millionaires" that cashed in on the success of the company, before joining forces to form Valve. Harrington is clearly the impetus behind the games' immersive nature. Here's what he said about the series in a previous interview:
Is this the game you have always dreamed of playing?
Mike - If only it came with a virtual [reality] body suit, then we could all live in the game. : )
When he's asked what the future of games looks like, he says, "I'm really looking forward to better physics simulations. There is a lot of room for improvement in this area. When objects in the game world start acting like objects in your world, an entire new set of possibilities get opened up."
Clearly a great deal of time, effort and thought have gone into the games in terms of gameplay, but that also indicates an equal amount of reflection on the plot and from where it borrows its ideas.
From here we turn to William Butler Yeats, one of the most renowned poets of the early 20th century. Specifically, we must concentrate our gaze upon his most famous work, "The Second Coming." Filled with allusions to grand human trials, the poem has given us many notable lines and ideas. (Here's a version of the poem recited by Law & Order's Sam Waterston, because he makes everything a little classier.)
Half-Life 2 begins with what might be a reference to the poem. The G-Man says to Gordon, "Your hour has come again." Compare this to Yeats: "And what rough beast, its hour come round at last."
Is Freeman that "rough beast"? Perhaps, but he's not Yeats' rough beast. Literary critic Yvor Winters wrote, "We must face the fact that Yeats's attitude toward the beast is different from ours: we may find the beast terrifying, but Yeats finds him satisfying - he is Yeats's judgment upon all that we regard as civilized. Yeats approves of this kind of brutality." Yeats, having been born into a time of Irish aristocracy, believed that the aristocrats were the highest order in the world and the bottom-feeders were the politicians who attempted and eventually succeeded in setting up a constitutional democracy. Half-Life's rough beast is not some crushing aristocratic class looking to rule over the commoners, but is one of those common men, seeking to destabilize the ranks of the overlords.