Senses in Decay

After the "resonance cascade", the H.E.C.U spread to almost all the sector of Black Mesa. The sector A was the most closest to the surface, that's why our protagonist manage to escape so easily.

John White escaped in a car, but he stopped in a storage facility of Black mesa. He destroy a vent to find supplies, but he find himself trapped in that supply room. The only way to escape is crossing all the F,G,H sectors of Black Mesa to the principal entrance.