Gordon Freeman is a coward. Or at least, he is when I play him. It's those damn poison headcrabs. As soon as they start hissing – shrouded in darkness, probably fresh off the assembly line from some Nightmare Factory – I turn into an orange-and-black blur and beeline for the nearest corner to cry in. When Alyx is around, I push her into the poison headcrab's Terror Lair and hide until she makes the bad things that can kill me in two hits go away. Meanwhile, in real life, I lean away from the screen until my spine feels like it's recently been on the receiving end of a Mortal Kombat Fatality. If you haven't gotten the picture yet, I really, really don't like poison headcrabs.
I love, however, that they exist. Half-Life 2's enemies in general are some of the most memorable I've ever encountered. In fact, I haven't experienced such a visceral reaction to any game enemy since.