Slither.io is a multiplayer game much like Agar.io but uses the mechanics from the classic game “Snake.”
Make sure you disable any other slither.io extension and scripts first!
How to install user scripts?
Firefox and related browsers: Greasemonkey.
Google Chrome, Chromium, and related browsers: Tampermonkey.
Opera (version 15 and later): Tampermonkey or Violentmonkey.
Opera version 12 and earlier supports user scripts natively. Violentmonkey provides a friendlier UI and better compatibility.