HALF-CHANGED

POWERED BY THE HλLF-LIFE® ENGINE

Half-Changed is a mod for Half-Life: Opposing Force loosely adapting the 2018 RPG Maker game Changed.
HC turns the Ao Oni and I Wanna Be the Guy-inspired furry puzzle game into a first-person shooter with puzzle, furry, and sometimes horror elements.
Though the mod itself may be about as SFW as the original Half-Life or Opposing Force, it is intended for adult audiences due to NSFW aspects of the source material Changed (though those aspects won't appear in the mod).

You play as Corporal Terrier, a 23 year-old operator of heavy equipment at Thunder Science Company. 5 years after the teleportation incident in 200X, Terrier has broken out of his cryostasis and now must find a way to escape the facility.

The setting of Thunder Science Company's facility is expanded upon, with most of the areas from the original game being turned into several maps.
Monsters (mostly those familiar to Half-Life players at the time of writing) roam the facility, often looking more to straightforwardly harm Terrier than to turn him into one of their own.
Unlike his canon counterpart, Terrier can fight back against the monsters with relative ease. Several of the weapons from Half-Life and Opposing Force have been modified, whether aesthetically or in function.
New music, made by the current sole developer Nimble-Bubble, is planned to accompany Terrier on his adventure.

This mod does not matter for the canon of Shell Island. It's merely made by the same people (or, at this point, person). The mod is planned to have at least 11 chapters upon its full release:

Awakening (hc_warehouse) - Warehouse, introduction of key mechanics
Cubicle Complication (hc_offices) - Offices, more open design, new "security complex" area
The Dark Nest (hc_dnest) - Dark Latex Nest, caves with various crystals and "gravity panels" (unusually-shaped ladders)
Close Quarters (hc_quarters and hc_maint) - New "living quarters" area, Library, and Maintenance Tunnels, you get to meet Puro as a security guard in this chapter
Greener Pastures (hc_greenhouse) - Greenhouse from Special Edition, featuring simulated natural environments (as an in-universe element, I don't think I can pull off a Rain World) and an overview of how the facility gets its food
Facility Innards (hc_innards) - A loose adaptation of the gas area with parts analogous to anatomical systems
Screams, Whispers, and Footfalls (hc_power) - The power/aquatic area given a more action-packed treatment, with the hub-and-spoke with Puro being greatly expanded upon in particular
The Pale World Left Behind (hc_jungle) - a more horror-themed take on the White Latex Forest/Jungle, with a boss at the end
Resumed Testing (hc_labs) - Laboratory, intended to be a more puzzle-oriented chapter
Communications Center (hc_comms) - Observation Rooms turned into a "communications center" in the vein of early versions of "Forget About Freeman!"
Termination by Sunset (hc_finale) - Equivalent to the "safe rooms" and ending of the original game, though more action-packed for a strong finale. May feature multiple endings...

Due in part to Valve's questionable Mac support for some of their games, some testing for this mod was done using the Xash3D FWGS engine by Flying With Gauss and Unkle Mike. You do not need Xash3D to play the mod.
A demo featuring the first two chapters is planned to be released in December 2025, with the full mod releasing at some point in 2026. Again, this mod is intended for adult audiences due to NSFW aspects of the source material.