It's been years since Kurt went through hell during the Black Mesa Incident, fighting for his life in the crumbling, dimly lit facility. He thought it was all over when he managed to escape that accursed place with several Marines and staff members in the back of a commandeered private jet... but alas it was only the beginning. Now, 10 years after the portal storms that wrought havoc all across the planet and the 7 Hour War that brought Earth to its knees, he stands atop a hill, looking at the newly constructed citadel over "City 27". He and his men had fought hard to disrupt Combine operations in the area and delay construction, but it wasn't enough. The Citadel was completed on schedule, and doing God knows what to aid the occupiers in tightening their control on Earth.
And yet... he is not dissuaded. The Combine's main forces have left the planet, leaving only a garrison comprised mainly of augmented humans and a relative handful of synths. So long as they can find a way to seal the Combine off and eliminate the garrison, there is a chance that the world will be free. It may be one in a billion that such a thing is possible... but so long as there's even just a smidge of a chance, it's worth fighting for...

Art by IgnisFelis