A/N: This crossover is part of an experimental series I'm working on. One that itself creates an AU.
Disclaimer: I do not own the Half-Life series or KonoSuba.
We know how it ended in the original Half-Life, the moment the Nihilanth was defeated, the invasion on Earth was over. But in this world, it ended much... MUCH earlier, when the Lambda Team successfully managed to launch the satellite before the military could abort it.
In just less than a single day, the Earth was finally at peace.
The problem is - The Nihilanth is still alive. 20 years had passed since the invasion ended. Black Mesa has been rumored to continue operating under new, competent management, and the forces of Xen had been strengthening itself in those past years.
Later expeditions by the survey team would confirm this, and so any and all expeditions to Xen were discontinued indefinitely.
In Xen, the Nihilanth had managed to amass a large and competent army, as well as fortification based on their attempted invasion on Earth, and lately, other worlds.
Among these other worlds, the Race X homeworld had been annexed by Xen as part of its mission to intensify its force, for reasons yet to be explained.
Even now, Xen continues to invade other worlds by using faults in each its realities to their advantage.
Especially, this Wonderful World.
"Attention, all adventurers! This is an emergency quest! Gather outside the main gate immediately!"
Introducing...
XEN ATTACKS!
Chapter 1 coming soon...