Nothing happened. Here is exactly what this page did:

✓ Printed some scary text on a black background.

✓ Read info your browser hands to every website you visit — screen size, timezone, language, CPU cores — and showed it back to you.

✗ Did not send a single byte anywhere. No network requests. At all.

✗ Did not touch your files, camera, microphone or passwords.

✗ Did not save or transmit your keystrokes — they were echoed on screen and thrown away.

It is one HTML file. Hit View Source and read the whole thing.