Yeah, Half-life's ending was a total disappointment. Opposing Force was a little crap too (but also highly sinister!), and at least Blue shift had a happy (if not stupidly premature) ending.
GTA - What ending?
But for the worst ending ever, you have to back to 1988 (or was it earlier?) to a game called "Eye of the Beholder"
An early RPG game which had you wansering around dungeons for hours, and hours, and hours. And what was the ending?
It exited to DOS and said "Well Done"
