online multiplayer game maker
Online multiplayer game maker: you make the game, Summer runs the servers
Describe the game you want to play with other people. Your agent builds the client and the server, and Summer hosts every match, so nobody has to run a server or share an address.
Most multiplayer ideas stall long before the fun part. Networking code, a server to rent, a way for players to find each other, saves that survive a restart: each one is a project of its own. Summer Engine is an online multiplayer game maker that puts all of that into the engine. You decide what players do together. Your agent writes the code. Summer runs the match.
A Summer multiplayer game is one project with two sides. The client is what every player runs: controls, camera, visuals and menus. The server runs without a screen and owns the rules: the score, the doors, who won. Summer starts a server for every match, so no player is the host and the game keeps going when someone leaves.
You build it by asking. Claude Code, Codex, Cursor or the Summer agent connect to the engine with one command and follow Summer's multiplayer skills step by step. Test with several players on your own computer, then publish on Summer Games, where your friends can join in the Summer Games app on Mac and Windows.
One prompt turns a game into a multiplayer game
Ask your agent to make the project multiplayer and it plans the split first: what moves to the server and what stays with each player. Then it sets up both scenes, the match queue and joining from your existing menu, and runs a first test with two players. The same code runs on your machine and once the game is published, so there is no separate server version to keep in sync.
Matchmaking, parties and teams are already there
Players find a match through queues you name, like casual or ranked 2v2. Summer supports quick play, ranked matches by skill rating, fixed teams and an accept prompt before a match starts. Friends form a party, the leader presses Play, and the whole party lands in the same match and on the same team.
Fair, fast and hard to break
Each player moves their own character the moment they press a key, and everyone else sees them move smoothly. The server checks every move and request, so a modified client cannot give itself points, speed or items. Shots and swings are checked against what the attacker saw on screen, so a hit that looked like a hit counts.
Progress, worlds and rankings that last
Save each player's coins, unlocks, level and settings from the server and bring them back in every match, on any device. Build a shared world, like a base, a farm or a realm, that saves while people play, sleeps when it is empty and wakes when they return. Add skill ratings for ranked queues and score boards for anything your game counts.
Test with many players, then publish
Local Play runs several players on your computer, including a bad connection, so you see what real players will see before anyone joins. When it plays right, your agent exports the game with its server and publishes it on Summer Games. It asks you before the game goes live. Players sign in once with their Summer account, see which friends are online and jump into your game together.
How it works
From prompt to playable in three steps
1. Connect your agent
Install Summer Engine and connect the agent you already use. It gets the engine tools, the docs and the multiplayer skills.
“Connect to Summer Engine and open my project.”
2. Make it multiplayer
Ask for the split. The agent reads your project, tells you what the server will own, then builds both sides and joining.
“Make my game multiplayer. Tell me what moves to the server first, then set it up and run Local Play with two players.”
3. Add the way people play together
Queues, parties, saves and rankings are each one request away. Test every step with Local Play.
“Add a ranked 2v2 queue with parties, save each player's unlocks, and show a leaderboard after each match.”
4. Publish and invite your friends
The agent exports the game with its server and prepares the Summer Games page. You approve, and the game is live.
“Publish this on Summer Games so my friends can play tonight.”
Examples
Prompts and what they generate
“A top-down arena shooter for up to eight players, short rounds, a score board after each round.”
A server that owns the score and the round timer, instant movement for each player, fair hit checks, and a results screen. Add ranked play next.
Start from an arena shooter template“A co-op platformer where two friends have to work together to open each door.”
Two players in one level, doors and switches owned by the server so both screens agree, and a party so friends always land together.
Start from a co-op platformer template“A shared survival world where my friends can build a base that is still there tomorrow.”
A persistent world that saves while people play and wakes up when they return, with each player's inventory saved across sessions.
Start from a base-building template“A 1v1 card game with hidden hands and a ranked ladder.”
Server-checked turns so no one sees the other hand, rated matchmaking, and a ladder with each player's place.
Start from a card battler templateFrequently asked questions
What is an online multiplayer game maker?
It is a tool that lets you build a game people play together over the internet without building the networking and servers yourself. In Summer Engine your AI agent writes the client and the server, and Summer hosts every match, with matchmaking, parties, saves and leaderboards included.
Do I need to run my own servers?
No. Summer starts a server for every match. No player hosts the game, nobody shares an address, and the match keeps going when someone leaves. A player who reconnects in time gets their seat back.
Can I make a multiplayer game without knowing networking?
Yes. Describe how players should play together and your agent follows Summer's multiplayer skills to build it: the server that owns the rules, joining, movement, shared state and testing. You can read and change every line of code it writes.
How do I test a multiplayer game?
Use Local Play. It runs several players on your own computer, and it can add a bad connection so you see lag the way real players would. The same code then runs unchanged once the game is published.
What kinds of multiplayer games can I make?
Competitive team shooters, battle arenas, party games with secret roles, co-op missions, card games with ranked ladders, and shared survival worlds that save. Each uses the same building blocks: queues, parties, server-owned state, player saves and ratings.
Where can people play my multiplayer game?
Publish it on Summer Games and players join in the Summer Games app on Mac and Windows with their Summer account. Your agent can prepare the store page and upload the build, and it asks you before the game goes live.
What does hosting cost?
Summer Engine is a free download. Hosted multiplayer is a Summer service: usage is billed from your Summer credits, and spend is visible in your dashboard.
Keep exploring
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OpenConnect your AI agent
Claude Code, Codex, Cursor or the Summer agent, set up with one command.
BrowseMake a game with friends
Build it together on one board, then play it together.
BrowsePublish on Summer Games
Your agent prepares the page and the build. You approve the launch.
BrowseArena shooter template
A fast start for a competitive multiplayer game.
BrowseStart building your game now
Download Summer Engine, describe what you want, and watch it come together. Free to start, no coding required.