When does something stop being "fan-made" and start being real? Considering the fact that the excellent Half-Life tribute Black Mesa was itself made by fans of the original game, this amazing alternate ending, created and uploaded by Machinima filmmaker TomahawxX, feels perhaps a touch more real than your average fan-made video.
The filmmaker, who created the whole thing without the aid of Valve's new Source Filmmaker tech, writes:
By deciding that Gordon Freeman remains silent during his adventures, Valve also abandoned the possibility of revealing his thoughts and inner life - with good reason. It allows the player to interpret and react on a situation by himself, supporting the identification of the character. But apart from that the fact that Gordon always stays calm and unfazed may lead to the impression that he is cold-blooded, a highly professional war machine, which surely wasn't Valve's intention. So this machinima aims at showing possible feelings and thoughts of the anti-hero, although this alternative ending is not true to the original story.
Check it out. It's powerful stuff.