While official multiplayer for the series (featuring Alex Mercer and James Heller) was famously cut during development by Radical Entertainment to focus on the single-player experience, the modding community and independent developers have filled that void with various projects. 1. Casualties: Unknown (Scav Prototype)
These mods are called "prototypes" not because they are unfinished, but because they exist as proof-of-concept—demonstrating that a game's engine, often believed to be hardcoded for one player, can be tricked into synchronizing two or more clients over a network. prototype multiplayer mod
Sgt. James Heller, a soldier infected by Mercer, hunts him down to avenge his family. a soldier infected by Mercer
[L0st_Visitor] : i’ve been alone for a long time was a notoriously single-player
No one believed it. The game, Cinderfall: Echoes , was a notoriously single-player, offline-only experience—a sprawling, melancholic open world about isolation. Its code was a legendary mess of spaghetti and duct tape. Multiplayer was a hallucination.
Features a story involving high-tech "precursor" vehicles and a new endgame storyline with 15+ hours of content. A multiplayer prototype for Hogwarts Legacy