After Gordon Freeman infiltrated and escaped Nova Prospekt, City 17 slowly erupted into a warzone that could no longer remain ignored by the Combine overlords.
Since Civil Protection was incapable of dealing with the magnitude of this calamity, all Overwatch soldiers were sent out to squash any rebellion no matter the destruction that would be needed, led closely by the most experienced leaders that included the Elites, rarely seen by normal eyes.
Get the Half Life Alyx soundtrack on Steam – https://store.steampowered.com/app/1310460/HalfLife_Alyx_Soundtrack