What Is an Authoritative Game Server? (And Why Multiplayer Needs One)

If you have ever asked "do I need an authoritative server for my game, and what even is one", this is the article. It is one of the most common questions on r/gamedev and Hacker News, and the answer decides most of your multiplayer architecture.

The one-sentence definition

In an authoritative model, the server owns the truth. Clients are, in Gabriel Gambetta's phrase, "privileged spectators": they send inputs (move left, fire, place block), the server runs the real simulation, and it sends the resulting state back to every client. No client gets to declare "I picked up the item" or "I hit you". It asks; the server decides.

Authoritative vs client-authoritative

The alternative is letting clients decide their own state and trusting them. That is simpler to build and almost always a mistake for anything competitive or shared.

Question	Client-authoritative	Server-authoritative
Who decides outcomes?	Each client, for itself	The server, for everyone
Cheating	Trivial (speed hacks, teleport, item duplication)	Server validates every action
Consistency	Clients can disagree about the world	One world, one truth
Build difficulty	Low	Higher (the topic of this article)
Right for	Single-player, fully trusted local co-op	PvP, shared persistent worlds, anything ranked

The moment players can affect each other and have a reason to cheat, you want the server to be authoritative.

Why a naive authoritative server feels laggy, and the three fixes

If the client has to send an input, wait for the server to process it, and only then move, every action feels delayed by your ping. Modern games hide this with three well-known techniques.

1. Client-side prediction

The client applies your input immediately and predicts the result locally, instead of waiting for the server. Your own character feels instant, exactly like single-player.

2. Server reconciliation

The client tags every input with a sequence number and keeps a copy. When the authoritative state arrives, it says "I last processed input number 42". The client accepts that state and re-applies inputs 43 onward. Mispredictions get corrected without a visible snap in most cases.

3. Entity interpolation

Other players are rendered slightly in the past (often around 100 ms) and smoothly interpolated between known positions, so they move cleanly instead of teleporting on each update.

These three ideas are the backbone of fast-paced netcode. Gambetta's Fast-Paced Multiplayer series and Chris's "Netcode Explained" videos are the canonical explainers if you want the deep dive.

Tick rate: how often the world advances

The server steps the simulation a fixed number of times per second. That is the tick rate. Valorant runs at 128 Hz. Most games sit between 20 and 64 Hz. A co-op survival or sandbox game is usually fine at 10 to 30 Hz. Higher tick rate means smoother, more responsive play and more server cost. You pick the rate your game actually needs, not the highest number you can imagine.

Why studios dread building this

Authoritative netcode is a discipline of its own. A recurring story on r/Unity3D is "it took me months to learn server authority", and another is a studio that cut multiplayer entirely because the servers got too expensive. Most indie teams do not have a dedicated networking engineer, and the work gets reinvented for every new title. That is exactly why managed options exist.

When you actually need one

• Competitive or PvP games: yes. Anti-cheat depends on it.
• Shared persistent worlds (survival, sandbox, social): yes. One consistent world needs one owner.
• Pure single-player or async games: no. There is nothing to keep in sync.
• Tiny, fully trusted co-op: maybe not. A listen server where one friend hosts can be enough, with the trade-offs covered in that article.

Where Crux fits

Crux Realtime is a hosted authoritative server. You define how your world behaves (handle a player joining, handle an incoming action, advance the world each tick), or describe the game in plain language, and Crux runs the authoritative loop, validates actions server-side, syncs state to every client, and scales instances on demand. You get the cheat-resistant, single-source-of-truth model without writing prediction, reconciliation, or socket code yourself. Player auth, saved progress, leaderboards, and economy are part of the same backend.

Next, see how a hosted authoritative server compares to the two older ways of running multiplayer in Listen Server vs Dedicated Server vs Hosted Authoritative.