> ## Documentation Index > Fetch the complete documentation index at: https://docs.summerengine.com/llms.txt > Use this file to discover all available pages before exploring further. # Share the game world > Scores, doors, pickups, private hands of cards and one-off effects: the server owns every fact, players ask it for changes, and everyone sees the same game. Apart from each player's own movement, **your server owns every fact in the game**: the score, the round timer, which doors are open, what's in each player's inventory, who won. Players never change those facts directly. They ask the server, the server checks the request against who they are and the current game, and then everyone sees the result. That's what keeps every player's game the same, and what stops a modified client from cheating. ## Games like this Shared tasks, doors and votes, plus secret roles. A shared board, with a private hand for each player. One kitchen everyone works in at the same time. Blocks, chests and items everyone shares. ## What your players get The server owns the facts. Shared facts like the score and a door go to every player. A private fact like one player's hand of cards goes only to that player. The server owns the facts. Shared facts like the score and a door go to every player. A private fact like one player's hand of cards goes only to that player. * **One game for everyone.** Every player sees the same score, the same open door and the same coin gone once it's picked up. * **Joining late just works.** A player who joins mid-match gets the current score, doors and everything else straight away. * **Secrets stay secret.** A player's hand of cards, wallet or secret role only ever reaches that player's device. * **Fair requests.** Picking up, buying, opening and voting all go through the server, which checks them first. ## Pick your setup Most games use all four of these together. ### Shared facts everyone sees The score, the round timer, a door, who's holding the flag. Your server keeps the value and every player gets it, including anyone who joins later. When the server changes it, every player sees the change. In my Summer multiplayer project, make \[THE FACTS, for example "the score, the round timer and the doors"] shared and owned by the server. Use the Summer `multiplayer-state` skill; if you don't have it installed, find it in the Summer library. * The server keeps each value and changes it. * Every player sees the same values, including players who join late. Read my project first and list every fact in my game and who should see it before you change anything. Then test it with Local Play and tell me what every window showed. ### Private facts only one player sees A hand of cards, a wallet, an inventory, a secret role. The server keeps it like any other fact but sends it only to the player it belongs to. If that player drops out and comes back, they get it back. In my Summer multiplayer project, give each player a private \[HAND / WALLET / INVENTORY / ROLE] that only they can see. Use the Summer `multiplayer-state` skill; if you don't have it installed, find it in the Summer library. * The server owns it and changes it. * Only that player's game ever receives it. Read my project first and tell me what goes in it before you change anything. Then test it with Local Play and check that no other window ever shows it. ### Requests: collect, buy, open, ready When a player wants to do something that changes the game, their game asks the server. The server knows exactly who is asking and checks the request against the current game: is the coin still there, is the player close enough, can they afford it? Then it accepts and changes the game, or refuses with a reason your game can show. A player asks to open a door. The server checks the request. If it accepts, the door opens for everyone. If it refuses, only the player who asked hears why. A player asks to open a door. The server checks the request. If it accepts, the door opens for everyone. If it refuses, only the player who asked hears why. In my Summer multiplayer project, let players \[COLLECT / BUY / OPEN / READY UP]. Use the Summer `multiplayer-state` skill; if you don't have it installed, find it in the Summer library. * The player's game asks the server; it never changes the game itself. * The server checks \[THE RULES, for example "the player is within 2 metres and the coin is still there"]. * If the server refuses, the player sees why. Read my project first and tell me which actions in my game become requests before you change anything. Then test it with Local Play and tell me what happened when two players tried at the same time. ### One-off effects A sparkle when a coin is collected, a sound, a hit flash. The server sends these to everyone once, as they happen. Unlike shared facts they aren't kept, so a player who joins later doesn't replay old sparkles. Use them for things that only matter in the moment. A player who joins mid-match gets the current score and door straight away, but not the sparkles that already happened. A player who joins mid-match gets the current score and door straight away, but not the sparkles that already happened. In my Summer multiplayer project, play \[THE EFFECT] for every player when \[IT HAPPENS]. Use the Summer `multiplayer-state` skill; if you don't have it installed, find it in the Summer library. The server triggers it; it's only for the moment and isn't replayed for players who join later. Read my project first, then test it with Local Play and tell me what every window showed. ## Not sure which fits? Read my Summer project and help me plan its multiplayer game state. Use the Summer `multiplayer-state` skill; if you don't have it installed, find it in the Summer library. Don't change any files yet. Tell me: 1. every fact in my game, and whether everyone sees it or only one player; 2. every action a player can take that should become a request to the server, and what the server checks; 3. the one-off effects worth sending; 4. anything my design needs that this doesn't cover yet, and how we can build around it. ## Testing it on your machine Local Play runs your server and several game windows on one computer. Check that every window shows the same shared facts, that private facts only show in their owner's window, and that two players trying the same thing at once get one clear answer each. Then run it again with added delay and packet loss. See [Make your game multiplayer](/build/multiplayer#testing-it-on-your-machine). *** Does this not help you? [Reach out on Discord!](https://discord.gg/summerengine) This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.