After being put to wait for more than a decade, it seems that fans have already got Half Life 3’s plot figured out. This is despite of the fact that Valve has yet to reveal anything on Half Life 3. However, the ending in Half Life 2 failed to cover the certainties on the plot of this future sequel.
If everything is spot on, Half Life 3 will start with Alyx grieving over her deceased father. She will then reunite with the G-Man and the protagonist as they look to end the war with the Combine once and for all.
Speaking of which, the alien race has already acquired the Borealis and is looking for a way to function it. This is something the protagonist must prevent if they wish to stop the destruction of a planet.
Eventually, the lead character will manage to destroy the Borealis, thus, forcing the Combine into full retreat. This will result in peace being restored in the Half Life universe.
Of course, this is merely a fan-made plot but there is no way for Half Life 3 to not feature the above events. Heck, such a storyline is also adopted by the developers of the Half Life fan-made films. All that is left is for Valve to produce Half Life 3.