Web game/app speed modifier. [Use responsibility, dont cheat multiplayer games]

game_speed_injection.js

window.__setGameSpeed = (speedMultiplier) => {
  window.__requestAnimationFrame ??= window.requestAnimationFrame.bind(window);

  const startTime = window.performance.now();

  window.requestAnimationFrame = function (callback) {
    return window.__requestAnimationFrame(function (timestamp) {
      const elapsedTime = timestamp - startTime;
      const fakeTimestamp = startTime + elapsedTime * speedMultiplier;

      callback(fakeTimestamp);
    });
  };

  console.log(`Game speed set to ${speedMultiplier}x.`);
};

Example:

__setGameSpeed(2);
__setGameSpeed(1);