my theory is:
Gordon sabotaged the experiment; he was already working for the Gman.
there are hints everywhere:
-you “wake up” on the tram at the start of both HL2 and HL1.
-gordon was late, the plan was already in effect.
-equipment malfunctions prior to experiment
-in DECAY, Rosenburg says the AMS was sabotaged. gman’s crystal, your hev suit.
-Gman is always watching you, even prior to the resonance cascade.
-gordon (You) cant talk or write for some reason (lolol hypnosis)
-some of Gman’s dialogue seems to allude to it.
-you have an almost messianic reputation prior to HL2, which i doubt was generated by the surviving science team alone; it all fits with Gman’s plan.
-even more shit
i could go on, but yeah. We know Gman used you to kill the Nihilanth and the combine. why? no clue.
i realize others may have come to this conclusion as well. It’s just a theory, but a perfectly logical one.
so yeah, get out your tinfoil hats and go crazy