This is alternative timeline if the black mesa incident never happens, Wallace Breen & Mossman we're arrested prior to their both plans were caught red handed by the black mesa authorities. And the scientist never turning on back the resonance cascade knewing it could resulting a massive disaster. And thus, the incident of black mesa never happens!(G-Man and All Xen creatures also never exist too in this alternate timeline where everyone joying the peaceful life, no war, just happiness ever after :)) Where do you want to visit?