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Rust · 2026
Bevy · SpacetimeDBBevySpacetimeDBWebAssemblyDistributed state

Eivar-Online

Multiplayer prototype: server-authoritative Rust simulation, replicated state, client-side prediction.

Source code
Eivar Online character select screen over the game's key artCrafting at the blacksmith: recipe list and the materials an axe needsGathering wood from an oak tree, with the channel bar runningLoot window after a kill: gold and a wood drop to takeInscriptions on a sword: an element for the weapon and words that change each abilityA mage staff's stats next to the equipment and inventory panelsBuying a mage staff at Market 1 from inside the gameThe same Market 1 order book on the Eivar websiteTraining ground with target dummies and the ability bar

01 / 09 Eivar Online character select screen over the game's key art

01The problem

How do you keep a shared game world consistent while making it feel responsive to each player? I am exploring authoritative simulation, replicated state and client-side prediction in Rust.

02What I built

An open-source multiplayer prototype written in Rust, with Bevy ECS for gameplay and SpacetimeDB for replicated state. I work on simulation, client-side prediction and game mechanics: crowd-control, ability kits, loot, gathering, crafting and player markets. A place to explore game development, networking and WebAssembly together.

  1. 01Server-authoritative simulation with client-side prediction
  2. 02Replicated state through a SpacetimeDB module compiled to WebAssembly
  3. 03Loot, gathering, crafting and player markets as bounded domain events
05What I learned

How ECS design, replicated state and client-side prediction fit together: the server enforces the rules while the client keeps play responsive.