JSFiddle - React, Tailwind, and code Playground

HTML

<canvas id="gameCanvas" width="400" height="600">We don't support old browsers</canvas>

CSS

* {
  margin: 0;
  padding: 0;
}

JavaScript

var canvas;
var canvasContext;

// Enemy Planets Variables
var planetX;
var planetY = 0;
var planetRadius = 20;
// Speed of planet descent
var planetSpeedY = getRandomSpeed(1, 7);
// Speed of planet descent
var planetSpeedX = getRandomSpeed(2, 8);


// Run On Load
window.onload = function(){
    canvas = document.getElementById("gameCanvas");
    canvasContext = canvas.getContext('2d'); 

    // Planet appearance on canvas
    planetX = canvas.width * Math.random();
    
    // Start Gameplay
    var framePerSecond = 30;
    setInterval(function(){
        drawEverything();
        moveEverything();
        //animatePlanets();
    }, 1000/framePerSecond);
    
    
}

// Drawing Canvas Rectangle
function colorRect(leftX, topY, width, height, drawColor) {
    canvasContext.fillStyle = drawColor;
    canvasContext.fillRect(leftX, topY, width, height, drawColor);
}

// Drawing Planet Circles 
function colorPlanet(centerX, centerY, radius, drawColor) {
    canvasContext.fillStyle = drawColor;
    canvasContext.beginPath();
    canvasContext.arc(centerX, centerY, radius, 0, Math.PI * 2, false);
    canvasContext.fill();
    canvasContext.closePath();
}

// Get Random numbers for Planets Speed
function getRandomSpeed(min, max){
    return Math.floor(Math.random() * (max + min)) + min;
}

// Drawing Game Canvas, Enemies and player
function drawEverything(){

        // Draw Game Canvas
        colorRect(0, 0, canvas.width, canvas.height, 'black');

        // Draw the Player
        colorRect(100, 200, 50, 50, 'white');

        // Draw the Enemy Planet
        colorPlanet(planetX, planetY, planetRadius, 'red');

}

// Moving the Enemy Planet
function moveEverything(){
    planetX += planetSpeedX;
    planetY += planetSpeedY;

    if(planetX < 0){
        planetSpeedX = -planetSpeedX;
    } else if(planetX > canvas.width) {
        planetSpeedX = -planetSpeedX;
    }

    if(planetY < 0){
        planetSpeedY = -planetSpeedY;
    } else if(planetY > canvas.height){
    ...