Greasy Fork

Whaddaya Think?

// ==UserScript==
// @name         Agar Cancer Mod (Tidied)
// @namespace    https://greasyfork.org/en/users/46159
// @version      1.2
// @description  Makes your eyes bleed
// @author       Turtle ? Clan & Tom
// @license      https://en.wikipedia.org/wiki/Free_and_open-source_software
// @match        http://agar.io/*
// @grant        none
// ==/UserScript==

window.addEventListener("load", function() {
    'use strict';

    var overrides = ['fill', 'stroke', 'fillRect', 'strokeRect', 'fillText', 'strokeText'];
    var ctxProto = CanvasRenderingContext2D.prototype;
    var oldMethods = new Map();
    for (let prop of overrides) {
        oldMethods.set(prop, ctxProto[prop]);
        ctxProto[prop] = function() {
            var gradient = this.createLinearGradient(0, Math.random() * this.canvas.height, Math.random() * this.canvas.width, this.canvas.height);
            gradient.addColorStop(0, "hsl(" + ~~(Math.random() * 301) + ", 100%, 50%)");
            gradient.addColorStop(1, "hsl(" + ~~(Math.random() * 301) + ", 100%, 50%)");
            this.fillStyle = gradient;
            this.strokeStyle = gradient;
            return oldMethods.get(prop).apply(this, arguments);
        };
    }
    var flute = new Audio('https://archive.org/download/cancerstorm_20160728/cancer.ogg');
    flute.volume = 0.3;
    flute.loop = true;
    flute.play();
});