--- title: Running a million-board chess MMO in a single process ·... description: A detailed technical postmortem on building One Million Chessboards, a real-time MMO where 150,000 players made 15 million moves on a 1000x1000 grid of chess... canonical: https://daily.dev/posts/running-a-million-board-chess-mmo-in-a-single-process-eieio-games-fj34qf09t twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Running a million-board chess MMO in a single process · eieio.games | daily.dev og:description: A detailed technical postmortem on building One Million Chessboards, a real-time MMO where 150,000 players made 15 million moves on a 1000x1000 grid of chess... og:url: https://daily.dev/posts/running-a-million-board-chess-mmo-in-a-single-process-eieio-games-fj34qf09t og:image: https://api.daily.dev/og/posts/fJ34Qf09t.png og:image:alt: Running a million-board chess MMO in a single process · eieio.games og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Running a million-board chess MMO in a single process · eieio.games **[eieio.games](https://daily.dev/sources/eieio-games)** · 30 min read · 0 upvotes · 0 comments ## Summary A detailed technical postmortem on building One Million Chessboards, a real-time MMO where 150,000 players made 15 million moves on a 1000x1000 grid of chess boards running in a single Go process. Covers the full architecture: a dense 8000x8000 uint64 array protected by a single RWMutex, zone-based move distribution to avoid O(N²) fan-out, protobuf+zstd serialization for bandwidth efficiency, Cloudflare caching for global data, and disk persistence via board duplication. The most technically challenging part was implementing rollback netcode on the client — optimistically applying moves immediately and maintaining a dependency graph to unwind conflicting moves. The author also reflects on game design mistakes: the lack of an awe-inspiring 'many players are here' moment and design decisions driven by scale rather than fun. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Teaching a Kotlin Chess Engine to Debug Itself](https://daily.dev/posts/teaching-a-kotlin-chess-engine-to-debug-itself-ez4uiidv5) · ProAndroidDev · 0 upvotes · 0 comments --- Tags: [#webdev](https://daily.dev/tags/webdev), [#golang](https://daily.dev/tags/golang) [View this post on daily.dev](https://daily.dev/posts/running-a-million-board-chess-mmo-in-a-single-process-eieio-games-fj34qf09t) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Running a million-board chess MMO in a single process · eieio.games","url":"https://daily.dev/posts/running-a-million-board-chess-mmo-in-a-single-process-eieio-games-fj34qf09t","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/running-a-million-board-chess-mmo-in-a-single-process-eieio-games-fj34qf09t"},"datePublished":"2026-03-31T12:29:41.739Z","dateModified":"2026-03-31T12:55:14.059Z","description":"A detailed technical postmortem on building One Million Chessboards, a real-time MMO where 150,000 players made 15 million moves on a 1000x1000 grid of chess...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/a81a5f4f2b97f4dad1639d0150a103ac?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/a81a5f4f2b97f4dad1639d0150a103ac?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"eieio.games","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"eieio.games","logo":"https://media.daily.dev/image/upload/s--gBaDB3pf--/f_auto,q_auto/v1774960055/logos/eieio-games?_a=BAMAMiWQ0","url":"https://daily.dev/sources/eieio-games"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/running-a-million-board-chess-mmo-in-a-single-process-eieio-games-fj34qf09t","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"webdev,golang","timeRequired":"PT30M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"eieio.games","item":"https://daily.dev/sources/eieio-games"},{"@type":"ListItem","position":3,"name":"Running a million-board chess MMO in a single process · eieio.games"}]} ```