 At the very end of "Half-Life 2", on top of the Citadel, he halts time completely during a huge explosion that would have killed Gordon and Alyx.The G-Man seems to be able to take people into "parallel universe"-like "voids" and put them into stasis.In most games featuring the G-Man, there are several sequences when he is talking at close range to the player, and various areas can be seen in the background, including areas from Black Mesa or even areas the player will visit later into the game.