well noticing how Gordon has already faced the harshest of trials including the almighty gargantua. I will be making guesses based on timeline. First is xen. Gordon had some guesses as to what kind of planet they live on like how it might be a swampy planet with very few minerals well look at xen in it's entirety. He will find out it is not really a planet but an alternate plain of existence where many different unseen species and floating rock platforms lie. but he will make a quote as to how he said there was possibly low gravity on the planet and he was right which is why he needed the jump module and when he sees the nihilanth he will most likely make quotes on how disgusting and baby looking it is. Next is the gman. he will remember how he has seen the gman around black mesa but apparently, only three times I think he has seen him walking away 1) on the first mission talking to the scientist 2)on the other side of a door which freeman tells him to open and how he thought it was a one-way window 3) when the two scientists were acting like voodoo zombies and such, or whenever else he remembers. When he remembers him the gman tells him all about what has been happening and if ross says there is no freeman's mind season 2:he will not accept the deal. If there is going to to be a season 2 then he will accept his deal and that is when he is put in cryo stasis and freeman abruptly stops his conversation with the gman where freeman will never again speak his mind until 20 years later. When he wakes up he quickly starts to figure out that the world has been taken over by the alien race known as the combine and how the earth was taken over in under 7 hours and slowly over the course he still has his ego but will still save the lives of the people around him and when he firsts witnesses alyx's near death he starts crying for her to come back and then he has only one goal:to defeat the combine and drive them off earth once and for all.