JavaScript is switched off

This one really does need it

The site is a 3D room with a MacBook you can sit down at and a terminal you can type into. All of it is drawn in your browser as you scroll, so with scripts blocked there is nothing here to show you. Two minutes of setting-changing and it works.

Turning it back on

Chrome

Settings → Privacy and security → Site settings → JavaScript → Sites can use JavaScript. chrome://settings/content/javascript
Edge

Settings → Cookies and site permissions → JavaScript → Allowed. edge://settings/content/javascript
Brave

Usually Shields rather than the setting: click the lion in the address bar and turn Shields down for this site. brave://settings/content/javascript
Firefox

Not in Settings, which is why it is hard to find. Open about:config, accept the warning, search for javascript.enabled and set it to true.
Safari

Mac: Safari → Settings → Security → tick Enable JavaScript. iPhone and iPad: Settings → Apps → Safari → Advanced → JavaScript, or Settings → Safari → Advanced on older versions.

Already on? Then something is blocking it for this page. uBlock Origin, NoScript and Brave Shields all do, and each of them puts a badge in the address bar you can click to allow the site.