G-man normally stands for Government man. I dont think he really is freeman from the future.
yeah i know, buts its a useless co-incedence.....
HOWEVER....how did he know were freeman would be at all those times in the game :P
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Its only taken me about 10 years to understand the water jug riddle in Die hard with a Vengeance. My brain takes a while, but it gets there in the end