WARNING: The following contains spoilers for Half-Life: Alyx.
This year's Half-Life: Alyx brings back the iconic series 13 years after Half-Life 2: Episode 2's cliffhanger in 2007. That game ended with Alyx cradling her dying father's body and Gordon Freeman falling unconscious. Now, Valve has made definite changes that shake up the story, taking it in a new direction.
Alyx is a VR game that tells a story set between the events of the first and second games. In it, Alyx Vance sets off to rescue her father Eli from Combine forces, but is told of a vault that houses something possibly dangerous to the Combine. Alyx sets about opening this vault, assuming Gordon Freeman is inside when Eli tells her that a person, not a weapon, is kept there. She successfully opens the vault and frees the one inside, who turns out not to be Gordon, but instead the mysterious G-Man. The G-Man offers her a service for freeing him, and this is where things change.
Though the game serves as a prequel to Half-Life 2, the G-Man seemingly knows what will transpire, and shows Alyx a vision of the end of Half-Life 2: Episode 2. He then says he can send her there to save her father and avert the vision, an offer she accepts. The G-Man tells her she's hired and implies she'll be a better employee than Gordon was. After the credits, things get interesting. Returning to the ending of Episode 2, Gordon wakes up in the White Forest Resistance base, where Eli seemingly realizes what has happened. Gordon gets his crowbar back as Eli tells him they need to kill the G-Man and get Alyx.
The complete rewriting of this ending means that Valve can tell whole new stories in this universe. The closing of the superportals means that the Combine are a contained threat with no back up coming, and the series looks to make the G-Man the villain. Also of note here is that Eli seems to realize that things have changed and that G-Man is responsible, so could be explored as well. Moving past the Combine as the big bad means there's so much more to explore in the Half-Life world.
Having G-Man as the villain will be interesting. He is a mysterious character we know almost nothing about, and that's part of what makes him so good. He seems to be an omnipotent force, but also mentions "restrictions" and "employers" several times, meaning there must be people above even him.
In an interview with Polygon, the developers talked about how the recent game changed the direction of the series. Alyx reintroduced and changed the ending of Half-Life 2: Episode 2, making the Combine a finite threat. The G-Man seems poised to replace them, but the challenge now seems to be making him the main villain without ruining the mystery of who he is and what he wants. There must be other ways to keep things moving without explaining everything about him the character.
It's also possible that the G-Man is not even the true villain. Eli and Gordon set off to kill him, which finally moves the story forward from the 2007 cliffhanger, but the G-Man could have an ace up his sleeve. Perhaps the G-Man is the reason Eli is aware that things changed. The biggest question moving forward may be just what the G-Man is planning here and what Gordon's role is now that he's free.
In an interview, Michael Shapiro, the voice of G-Man, mentions how the mysterious nature of the character is what draws people in. Shapiro expresses optimism that more games are coming, even hinting at what could be ahead. We could finally learn about who and what G-Man's "employers" are, and where Alyx was sent. Gordon Freeman disappeared at the end of the first game and reappeared at the beginning of the second, so the nature of how the G-Man conducts business may be worth exploring.
Half-Life: Alyx completely changed the story and how the Half-Life series will move forward. At long last, the Combine can truly be dealt with, and the story can go beyond Episode 2's memorable cliffhanger. As it stands now, the ending sets up so many possibilities and directions for where the next game could go and what to make of the G-Man.