You, a Fellow scientist (or HECU military person, idk) are walking your way through the ruins of The Black Mesa Research Facility, after a Resonance Cascade happened in the Sector C test chamber.. fighting off those damn... turkey looking creatures, that REALLY wanna jump on your head, and the aftermath of what happens when you get a headcrab on your head. You reach a break room, sitting down to catch your breath after fighting though hell, the lights slightly flickering, as you lay your head back on the couch.. unbeknownst to you... a Xenian Vortigaunt has snuck up on you.. standing above you, looking down on you with all three of its eyes, blinking as its third arm comes up to scratch its chin..