It's become a running joke and/or grim inevitability that Half-Life games will be indefinitely delayed. Fans are still anxious with anticipation about an announcement of a third in the series, or at least a third chunk of the episodic content that followed the second game - Valve doesn't seem to be in any hurry to make such a thing, or even to announce they're beginning to consider the possibility of more Half-Life. Players should really be used to that by now, what with the achingly long delay between the first two games, prolonged by the leaking of Half-Life 2's source code halfway through development. If it seems like something that began with the sequel, it isn't. The original Half-Life has a similarly epic development cycle, involving the complete do-over of the Quake engine the game was due to use, a relatively inexperienced team (it was their first title, after all, and really ambitious to boot), and - following a demo at E3 in 1997 which consisted of a single level throwing in every weapon, enemy and gameplay mechanic they'd come up with to date - Valve went back to the drawing board and started from scratch, throwing out years of work and delaying release by another year.
Tom Baker is the Comics Editor at WhatCulture! He's heard all the Doctor Who jokes, but not many about Randall and Hopkirk. He also blogs at http://communibearsilostate.wordpress.com/