The Cliff That Ended It All

So this story begins with this one man who worked in a laboratory at the time, he accidentally spilt and broke different vials which mixed, turning into a poisonous gas, knocking him unconscious for a good while. But what he didn't know was that this slip up would change the world.... Fast forward to now, he's alone and surviving on the bare minimum until he hits his head after tripping and falling down a cliff, concussed, he looked up to see a blurred out figure helping him to his feat and for the rest of the journey, or was the person just a figure of his imagination...?