In Rover: The Express server serves static files. But for Unity, you need to check: MIME headers .wasm support. Therefore, I think you should add the following to the server script:const express = require('express'); const path = require('path'); const app = express(); const PORT = 3000; const contentPath = path.join(__dirname, 'content'); app.use(express.static(contentPath, { setHeaders: (res, filePath) => { // WebAssembly (OBLIGATOIRE) if (filePath.endsWith('.wasm')) { res.setHeader('Content-Type', 'application/wasm'); } // Unity data files if (filePath.endsWith('.data')) { res.setHeader('Content-Type', 'application/octet-stream'); } // Disable cache (debug friendly) res.setHeader('Cache-Control', 'no-store'); } })); app.listen(PORT, '127.0.0.1', () => { console.log(`Unity WebGL server running at http://127.0.0.1:${PORT}`); }); module.exports = PORT;