Deterministic Multiplayer Framework

Server-authoritative simulation for Unity 6. Works with any netcode.

The hard half of multiplayer, already built.

Most multiplayer starter kits hand you a networking library and leave the hard

parts to you: keeping every player in sync, deciding who is authoritative about

a hit, and stopping cheaters. A networking library moves bytes. It does not

decide who is right. That decision layer is what this framework is, and it is

already built, already running, and already cheat-resistant.

SET UP IN A FEW CLICKS — NO CODING

Import the package and open United Games Studios > Framework Manager. The Build

My Game wizard walks you through a short checklist, builds the scene, and wires

everything up. A few clicks later you press Play, click Host, and you have a

running server-authoritative multiplayer game with a join code your friends can

use.

No coding at any point. No third-party networking package to buy or install —

LiteNetLib (UDP) is bundled and is the default online path, with UPnP and STUN

so join codes work across the internet without relay fees.

READ THIS BEFORE YOU DOWNLOAD

This is a multiplayer foundation, not a finished or polished game.

Characters are capsule primitives with simple materials. The package ships no

character models, no animations, no audio, and no level art — the only included

art is a health-bar UI. What you get is the simulation, the authority model, and

the architecture underneath a game, all working and all covered by an automated

test suite. The look of your game is yours to build on top.

If you want a playable game you can reskin, this is not that. If you want the

multiplayer engineering solved so you can focus on your actual game, this is

exactly that.

HOW IT WORKS

A deterministic, fixed-step simulation runs on a tick loop with a

server-authoritative model. Clients send input. The server runs the simulation

and decides outcomes. Results replicate back to everyone.

It is the same architecture competitive shooters and MMOs use to stay fair and

consistent under latency — here it is already wired up and running.

SEE IT WORKING, NOT JUST RUNNING

The online templates ship with a teaching overlay that names the feature you are

looking at while you play. Watch prediction correct itself, watch interpolation

smooth a remote player, watch lag compensation rewind a shot. Turn on 200 ms of

latency and 5% packet loss from the Inspector and watch all of it hold.

Most frameworks ask you to trust that the netcode works. This one shows you.

TWO PLAYABLE STARTING PATHS (FREE)

Both are created from Framework Manager > Build My Game. You do not need to hunt

for template scenes by hand.

Arena Shooter — a live server-authoritative multiplayer game. Host or join with

a code, move, shoot, and fight networked NPCs. Runs on the bundled LiteNet

transport with no extra install.

Offline Prototype — the same systems running single-player with no networking

at all. The place to learn how everything fits together before you go online.

Optional FPS sample scenes remain in the package if you prefer to open them

directly. Build My Game is the supported day-one path.

WHAT'S INCLUDED

Deterministic tick loop — a fixed-step simulation heartbeat at a tick rate you

choose (30 Hz default, fully configurable). The same inputs always produce the

same result.

Server-authoritative movement — responsive under latency through client

prediction and server reconciliation, without ever trusting the client.

Reconciliation thresholds scale automatically with velocity. No teleport or

speed cheats.

Lag compensation — when a client fires, the server rewinds other entities to

where that client saw them at their fire tick and resolves the hit against

those positions. Players do not have to lead their targets by their own ping.

The compensation window is bounded and configurable.

Smooth remote players — incoming snapshots are buffered and interpolated

between two known states rather than extrapolated, so remote players do not

overshoot and snap back when they change direction. Bounded extrapolation

covers packet loss.

Server-validated combat — hitscan and projectile weapons, plus melee, all

resolved on the server against authoritative positions. Clients cannot fake a

hit. All client input is range-clamped and sanitised server-side.

Networked NPC AI — a ready-made enemy with chase, melee, and wall-climb

behaviour, simulated on the server and replicated to every client.

Factions — assign players and NPCs to teams with friendly, hostile, and neutral

stances.

Death and respawn — full death detection and respawn scheduling, built in.

First or third person — choose the perspective when you create your character

and the camera, pivot, and input are wired for you. Inverted vertical look is on

by default and configurable.

Pluggable gravity — swap uniform gravity for custom sources without touching

movement code.

Session handling — clients detect when the host leaves, stop cleanly, and

report why instead of continuing in a dead session.

Test under real conditions — inject latency, jitter, and packet loss from the

Inspector and test your game at 200 ms and 5% loss without leaving the Editor.

Stability groundwork — basic area-of-interest filtering and time-dilation

safety help keep the simulation stable under load instead of breaking.

Framework Manager — Build My Game, Workbench, Guided Lessons, and Validation in

one place, with a first-run screen that puts you straight into Build My Game

rather than a wall of tabs.

Presentation that works offline and online — the same player views, cameras,

weapon visuals, and damageable presentation drive Free templates without

requiring FishNet.

DATA-DRIVEN — NO CODE REQUIRED

Weapons, factions, NPC behaviour, and movement are authored as

ScriptableObjects. Duplicate an asset, change the numbers in the Inspector,

press Play. You can build and balance an entire game without writing a line of

code.

CLEAN, EXTENSIBLE ARCHITECTURE

Systems talk through well-defined interfaces rather than tangled direct

references. Add your own simulation phases, swap implementations, or build on

top.

The transport sits behind an interface, so the networking library is your

choice. Bundled LiteNetLib is the default and needs no extra install. A FishNet

adapter is included for developers who already use FishNet or want its feature

set — install FishNet and the framework detects it automatically. The simulation

and authority layer stays the same underneath either one, so you are not locked

to one networking library.

Full C# source included.

WANT LARGER GENRES LATER?

Free is built to ship a real authoritative multiplayer game (Offline + Arena).

Deterministic Multiplayer Framework Pro adds Co-op Survival, Battle Royale,

Extraction Shooter, MMO-style plans, and scale systems on the same tick loop

and Framework Manager. Everything you build on Free carries into Pro.

DOCUMENTATION

GETTING_STARTED.md is written for developers who have never built a networked

or deterministic game. It covers core concepts, both Free starting paths,

Framework Manager, customisation, troubleshooting, and how Free relates to

Pro. A README at the package root maps every document to the question it

answers. Additional docs live under Docs/ (API map, networking default, Arena

smoke test).

REQUIREMENTS

Unity 6 or newer, Universal Render Pipeline (URP).

Requires the Unity Input System package. This framework does not support the

legacy Input Manager. Active Input Handling must be set to "Input System

Package (New)" or "Both".

Required Unity packages, installed automatically via Package Manager and not

redistributed by this asset: Input System, Newtonsoft Json, Mathematics, Burst,

Collections, and uGUI. Installing the Input System may prompt Unity to restart

the Editor.

WebGL is not supported for online play on the bundled transport.

NOT INCLUDED

Character models, animations, audio, level art, cloud matchmaking, dedicated

server hosting, or cloud account services.

Free genres are Offline Prototype and Arena Shooter. Co-op, Battle Royale,

Extraction, and MMO-scale modules are part of the Pro package.

THIRD-PARTY SOFTWARE

This asset uses LiteNetLib under the MIT License, NATS.NET under the Apache

License 2.0, Npgsql under the PostgreSQL License, and StackExchange.Redis,

Pipelines.Sockets.Unofficial and .NET runtime libraries under the MIT License.

See Third-Party Notices.txt in the package for details.