While there is no official multiplayer for the game series, the most relevant current project is the multiplayer mod for Scav Prototype (also known as Casualties: Unknown ), a popular indie survival horror game.
If you are looking for multiplayer options for the original Radical Entertainment Prototype games (Alex Mercer/James Heller), no functional multiplayer mod currently exists due to the complex nature of the game's engine. Scav Prototype (Casualties: Unknown) Multiplayer Mod
A fan-made multiplayer mod has been developed for this title, which is currently in a "prototype" phase itself. Creator: The mod is primarily attributed to krokosha666.
Status: It is in early testing and can be buggy; common issues include avatar glitches and connection difficulties.
Installation: To use it, you typically need the BepInEx mod loader.
Features: It allows for cooperative play and includes specific Multiplayer Challenges like the "Duo Descent".
Compatibility: It is playable on PC and can be configured for the Steam Deck with specific launch commands. Other Related "Prototype" Multiplayer Mods Hogwarts Legacy: A multiplayer prototype called
was released shortly after the game's launch, focusing on co-op and roleplay for up to eight players. Garry's Mod : There are long-standing Prototype-themed mods for Garry's Mod
that allow players to use Alex Mercer's powers in a multiplayer sandbox environment.
Subnautica: The Prototype Expansion Mod adds new facilities and a "prototype vessel" to the game, though its primary focus is expanded single-player content rather than networking. mod, or Multiplayer Mod with the developer of Casualties Unknown
Developing a multiplayer mod for (or any single-player-only game) is a high-level engineering challenge that typically involves "shoehorning" networked communication into an engine never designed for it. There is no official "multiplayer mod" for the
franchise, but you can build a prototype of one using the following technical framework. 1. The Architectural Strategy: "The Trainer Approach" Most successful multiplayer mods for older titles use a trainer-based architecture . This avoids rewriting the entire game engine. The Client Application : A custom program that runs alongside prototype multiplayer mod
. It reads your player's data (X, Y, Z coordinates, rotation, current animation ID) from the game's memory. The External Server
: A simple central node that receives data from all connected clients and broadcasts it to everyone else. Synchronization
: Your client receives coordinates for other players from the server. It then uses the game's memory to "spawn" an NPC (like a civilian or soldier) and force that NPC's position and model to match the other player's data. 2. Required Development Tools
To start building this, you will need tools to interact with the game's memory and networking: Cheat Engine
: Vital for finding "pointers"—the memory addresses for health, position, and power states. Visual Studio Community
: The standard IDE for writing the C++ client and server code. Networking Libraries : Use lightweight libraries like LiteNetLib for fast, low-latency UDP packet handling. 3. Implementation Workflow Memory Hooking
: Identify the static addresses or pointers for your player's coordinates. Entity Spawning
: Find the game function that spawns an NPC. You must "hook" into the prototypeenginef.dll
to trigger this function on command when a new player joins the server. State Replication
: Periodically (e.g., every 15ms) send your position to the server. When the server sends back another player's position, update the corresponding NPC in your game world. Animation Syncing
: This is the hardest part. You must find the memory address for the current "animation state" and replicate it so other players don't just "T-pose" while moving. Steam Community 4. Current Community Status Mod Compatibility : A recent surprise Steam update for While there is no official multiplayer for the
(September 2025) broke many existing mods and DLL hooks. Ensure you are testing on a version compatible with the Resolution and FOV Fix Existing Frameworks : While no full MP mod exists, many players use to swap character skins (e.g., playing as Alex Mercer in Prototype 2 ), which is often the first step in visual synchronization. Steam Community memory addresses/pointers for player coordinates to begin your first test script?
Most prototype multiplayer mods progress through predictable stages:
The Prototype Multiplayer Mod is not a "good" mod in the traditional sense of adding seamless content. It is a broken, beautiful window into what Prototype 3 should have been.
It exposes the limitations of the 2009 engine, but it also highlights the timeless fun of the movement mechanics. If you have a friend who also remembers the "Tendril Barrage" fondly, and you don't mind spending 20 minutes setting it up, this mod offers a chaotic, buggy, and utterly unforgettable afternoon in New York Zero.
Pros:
Cons:
Final Thought: It turns Prototype from a solo guilt-trip into a chaotic buddy comedy. It’s the closest we will ever get to a Prototype sequel, and for that, it is essential.
While there is no official multiplayer mode for the series, several community-driven projects and mods have attempted to bring co-op or versus play to the game. Community "Prototype" Multiplayer Mod Projects "Prototype 2 Co-op" Reddit Project
: A recurring topic in the community, with some users claiming to have developed early-stage functional co-op prototypes for Prototype 2 WARSHIFT Co-Op Prototype : A separate game titled
released a playable prototype of a co-op mode inspired by similar mechanics, where a commander controls base development while other players use "Combat Avatars". Garry's Mod "Prototype" Workshop Mod
: One of the most popular ways to experience "Prototype" in multiplayer is through the PROTOTYPE Steam Workshop mod Garry's Mod The Typical Lifecycle of Such a Mod Most
. It recreates Alex Mercer's abilities—including gliding, shield bashing, and consuming NPCs—in a sandbox multiplayer environment. Steam Community Essential Modding Tools
If you are looking to mod the original game (even for single-player enhancements like 4K textures or stability), these are the standard tools:
: Used extensively to install custom skins (like the black jacket with dragon print) and high-resolution texture packs. Prototype2Fix
: A necessary community patch for modern systems to prevent crashes, black screens, and infinite loading loops. Discord Communities
: Most active development for multiplayer-style mods happens within dedicated fan Discord servers. Status of Official Multiplayer
Promising foundation, but needs stability and clarity before scaling.
The mod successfully demonstrates core multiplayer functionality (e.g., syncing player positions, basic chat, or shared world state). However, as a prototype, several areas require attention to move from “proof-of-concept” to “playable experience.”
Developer: Community / Fan Project Game Base: Prototype (2009) Status: Often experimental/alpha builds
For over a decade, Prototype has held a unique title in the gaming world: the best "terrible movie" simulator ever made. It was The Incredible Hulk meets The Thing, wrapped in an edgy 2000s narrative. But it always had one glaring omission. We could run up the Empire State Building, elbow-drop a tank from 500 feet, and consume a general to steal his memory—but we couldn't show our friends.
The Prototype M (Multiplayer) Mod attempts to fix the game's biggest tragedy by turning the single-player sandbox into a chaotic dual-player slaughterhouse. Having spent time navigating the buggy, exhilarating reality of this mod, I can confidently say: It is the best way to replay a classic, even if it falls apart if you look at it too hard.
Imagine two players in a Prototype multiplayer mod. Player A uses "Hijack" to grab a tank. Player B, across the city, uses "Devastator" to explode 50 infected. The game’s physics engine now has to calculate the position of every debris chunk, car, and NPC across two separate game states. Without true server-authoritative networking, desyncs happen within seconds. One player sees a helicopter shooting at them; the other sees the helicopter frozen in mid-air.
The most famous and ambitious attempt to date is the Prototype: ReBirth Multiplayer Mod, led by a team of four modders under the pseudonym Team Tendril. This project aimed to rebuild the game's networking layer from the ground up using a proxy server architecture.