This issue is specific to the itch app, and occurs when launching WebGL builds made with Unity 2020 and 2021 (Decompression Fallback enabled).
The following errors appear under the JavaScript Console tab in Developer Tools (press Shift+F12 after launching the game):
SnapWords.loader.js:1 failed to asynchronously prepare wasm: CompileError: WebAssembly.instantiate(): Wasm code generation disallowed by embedder SnapWords.loader.js:1 CompileError: WebAssembly.instantiate(): Wasm code generation disallowed by embedder at blob:itch-cave://game.itch/5a05f7d0-ceae-49fc-8481-c88094ce1483:2:24961
This appears to be a Content Security Policy (CSP) issue with the Chromium integration in the itch app.
Examples:
- https://cosmicadventuresquad.itch.io/deepest-sword (Made with Unity 2021.1.4f1)
- https://quite-good.itch.io/swing-shroom (Made with Unity 2020.1.17f1)
This issue does not occur with WebGL builds made with Unity 2019:
- https://zenasprime.itch.io/threshold-runner-lite (Made with Unity 2019.3.7f1)
navigator.appVersion "5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) itch/25.4.1 Chrome/85.0.4183.84 Safari/537.36"