multiplayer

Guidance for building games that multiple players experience over a network. It explains how game state and player input stay synchronized, how to deal with delay, and where the server's authority should live.

In plain words
What is it for?
Use it when choosing dedicated, host-based, peer-to-peer, or distributed servers; synchronizing state; hiding network delay; setting bandwidth limits; adding matchmaking; and designing server-side cheat protection.
Why use it?
It helps prevent jitter, players snapping backward, wasted network traffic, weak cheat protection, and hosting choices that do not fit the game.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/phuonghx/aim-cli/multiplayer
Any agent
npx skills add phuonghx/aim-cli --skill multiplayer
Clone the repo
git clone --depth 1 https://github.com/phuonghx/aim-cli

Made for: Claude Code, Codex.

Per session 80 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,298 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00080 $0.01298
Opus 5 $0.00040 $0.00649
Sonnet 5 $0.00016 $0.00260
Haiku 4.5 $0.00008 $0.00130

Measured yesterday against content hash 48c5694e207f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

multiplayer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

aim/templates/aim-agents/skills/game-development/multiplayer/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Networked Multiplayer

Practical reference for wiring up a multiplayer game: where authority lives, how clients stay in sync, how to spend bandwidth wisely, and how to keep cheaters from rewriting the rules.

Picking a topology

Match the network model to how the game is actually played:

  • Twitch / ranked PvP (fighting games, shooters, racing) -> run an authoritative dedicated server. Players never talk directly; the server owns the truth.
  • Drop-in co-op or friendly lobbies -> use a listen server, where one player's machine doubles as host. Cheap and quick to stand up.
  • Turn-by-turn play (card games, async strategy) -> a plain client-server loop is plenty; no tight timing budget.
  • Persistent worlds at scale (MMO) -> spread load across sharded / distributed servers, each owning a region or instance.

How the three common hosting styles stack up:

Model Round-trip latency Operating cost Cheat resistance
Dedicated server Consistently low Expensive to host High
Peer-to-peer Unpredictable Nearly free Poor
Listen / host-based Middling Cheap Moderate

The pattern: spend money to buy latency and trust. P2P flips that — it costs almost nothing but gives up both.

Keeping clients in sync

Two opposite philosophies, plus the blend almost everyone ships:

Strategy What travels the wire Where it shines
State replication Snapshots of the world (positions, HP, flags) Small object counts, easy to reason about
Lockstep / input replication Just the button presses, replayed in lockstep Deterministic RTS and fighting games
Hybrid Inputs locally, state for everyone else The default for most titles

Hiding the latency

Even on a dedicated server, the round trip is real. Four techniques paper over it:

  • Client-side prediction — the local player moves the instant a key is pressed, guessing what the server will confirm, so input feels immediate.
  • Entity interpolation — remote characters are rendered a beat in the past, blending between received snapshots so they glide instead of teleporting.
  • Server reconciliation — when a prediction turns out wrong, the client quietly snaps back and re-simulates from the authoritative state.
  • Lag compensation — for hit registration the server rolls the world back to what the shooter saw at fire time, so well-aimed shots count despite ping.

Read the full file on GitHub · 116 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 116 lines · 80 tokens per session scan A 48c5694e207f

Subscribe to this mod's changes

multiplayer is a skill published in the GitHub repository phuonghx/aim-cli (1 stars, last pushed 2mo ago), licensed MIT. It adds 80 tokens to every session and 1,298 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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