so i was thinking and i believe that the greatest way to end Half-life would be, Gordon traps the Combine leaders on earth. He sets up the final shot, fires. You hear a buzzing noise, then the screen goes blurry as and a new image comes through. YOU’RE BACK IN BLACK MESA DORMS, and your alarm is going off. After that you get up get ready for your shift. go through the intro to HL1, do the experiment and NOTHING GOES WRONG!
Gordon knew what could have happened if something went wrong. With all the stress, he dreamed up a scenario of what could have happened.
or even go all the way to MIT graduation day.