You are here today reading this book because you want to make video games. You wish to build your own video game, which can be run both in people's browsers as well as on their smartphones and tablets. All of this is possible today, though it has not been for the longest time. The reason you can now build your own game with relative ease is two fold: HTML5 and ImpactJS.

HTML5 is the latest version of our World Wide Web Hyper Text Markup Language and is the universal language for web pages. HTML has been around since the beginning of the 1990s when a CERN (the European organization for nuclear research) employee by the name of Tim Berners-Lee first introduced it. New versions were released quite rapidly: Version 2 in 1995, Version 3 in 1997, and Version 4 later that year. We had been using roughly the same version of HTML for over a decade until finally HTML5 saw the light in 2008. With the growing need for multimedia implementation, companies had been building browser plugins to play music, show movies, and so on. The Flash player is probably one of the best known plugins on this front. As a game developer you can still opt for using Flash and ActionScript, but we don't know how long Flash still has until (if ever) it will be fully replaced by HTML5. What will happen to Flash games remains hard to predict but one thing is pretty certain: the future of HTML5 based games looks bright. Since HTML5 emerged, browsers have been slowly increasing compatibility for it. HTML5 is a huge step forward as it introduces new elements to allow playing music and videos on the web pages themselves.

However, the most important new feature for us is the introduction of the <canvas> element. The <canvas> element is basically a placeholder for your graphical elements to appear on. Together with the use of JavaScript, it became possible to build browser games outside of Flash players. However, JavaScript in itself is not geared towards building games. In its raw form, you would be able to use it to build a game but it would prove dauntingly difficult. Thus, the last necessary ingredient is a JavaScript library with the sole purpose of game development. This is where ImpactJS comes into play.

ImpactJS is in essence a library of JavaScript code capable of making your life as a game developer a lot easier. ImpactJS was developed by Dominic Szablewski, a German genius, to say the least. The ImpactJS game engine has the advantage of enabling you to build a game very quickly with only a basic knowledge of JavaScript and HTML. This allows even a newbie programmer to focus on what they love: building the actual game. ImpactJS also comes with a very intuitive level editor and debug system, which we will also get into during the course of this book. ImpactJS is designed to build tile-based two-dimensional games. For instance, if you like to build a side-scrolling game such as Mario or a top-down game such as Zelda, you will want to go with ImpactJS. Now without much further ado, let's dive into the action by moving on to Chapter 1, Firing Up Your First Impact Game, where we will prepare ourselves for game development by gathering the necessary resources for it.

  EntityPlayer = ig.Entity.extend({
    size: {x:20,y:40},
    offset:{x:6,y:4},
    vel: {x:0,y:0},
    maxVel:{x:200,y:200},
    health: 400,

.defines(function(){
GameInfo = new function(){
  this.score = 0;
},