Guide 14 · Rookie
Troubleshooting the emulator
≈ 2 min readWhat to do about a case that won't boot, choppy performance, missing sound, or a browser that blocks it outright.
Running 1980s DOS software inside a browser through WebAssembly is remarkably solid, but it is still emulation on top of the web platform, and both layers can occasionally get in each other's way. Here is what each failure actually looks like and what to try.
01
The screen never gets past "Loading emulator runtime…"
This means the js-dos runtime script itself hasn't loaded. An ad blocker, script blocker, or strict tracking-protection extension can catch it because it loads as a module script. Try disabling extensions for the site, or open the page in a private window with extensions off, then reload.
02
You see "Emulator runtime not found"
That specific message means the runtime script loaded but never defined itself, almost always a content blocker or a broken cached copy rather than anything about your save or the case itself. A hard refresh (bypassing cache) is the first thing to try; if it persists, it is worth reporting rather than replaying, it is not something you caused.
03
You see a message about the case's files not being available
A handful of titles in the archive are catalogued but not currently bundled for in-browser play, and the boot screen says so plainly instead of hanging. There is a Retry boot link if you think that was a fluke; otherwise, read the game's dossier page instead, the write-up doesn't need the emulator.
04
The game runs, but it stutters
Close other heavy tabs, since the whole PC is being emulated in your browser tab's own thread budget. Try toggling Turbo Mode on the in-game toolbar, and check the Worker thread option under Settings, moving the emulation on or off the main thread can smooth out a stutter depending on your device.
05
There's no sound
Browsers block audio from starting on its own until you interact with the page. Click once inside the game window (which also captures your mouse) and sound should start. If it's still silent, check the Volume slider in Settings isn't at zero, then check your system and browser tab aren't muted.
06
Your mouse feels stuck or the pointer won't move the cursor on screen
That's mouse capture working as intended, not a bug: once captured, your mouse drives the in-game pointer only. Press Esc to release it back to your normal cursor, and if movement feels too fast or slow once you recapture, adjust mouse sensitivity in Settings.
07
A save is missing after you sign in
Guest saves are lifted to your account once, automatically, the first time you sign in from the same browser you played in. If you played as a guest on one device and signed in on another, that device never had the save to migrate. Before switching machines, sign in first so the save follows your account, or use Export on the launch bay's Save states panel to keep a copy yourself.