Oct. 10, 2023

tl;dr: have some CSS animations to make your browser games juicy!


My favourite game engine is the browser. You get so many batteries included when you use the browser as your runtime. Sprites, animation, sound, mouse, keyboard, touch, gamepad, fonts, text handling, localization, concurrency, networking, 2d, 3d, and a weird XML based scene-graph called "The DOM". The list goes on.

I'm not even talking about canvas based games. These days when I build games like Rogule, Asterogue, and Smallest Quest, I sometimes use <canvas> but I always use the DOM.

One cool thing I've discovered about using the DOM as your 2d game's scene graph is you can offload a lot of CPU intensive effects to a high performance declarative graphics language called CSS. This frees you up to write far less code, and do the more interesting stuff with game logic in your procedural code.

Smallest Quest

It was Juice It or Lose It that inspired me to put more juice into my games. The talk makes the case that "game feel" is a major part of what makes games fun. Game feel is a mixture of animation and sound in response to interactivity and in-game events. It's the difference between a flat game and one that pops.

When I started building Asterogue (a solo-developed space based sci-fi roguelike) I got to wondering - is CSS good enough for video games? I was using web tech to build the game already. Could I do all of the visual effects using only CSS animations?

Asterogue game play

I put together this collection of juicy CSS game-feel animations as a test and I've been building on them ever since. Feel free to use them in your own browser games!


Before I made Asterogue I would have used JavaScript to manually script sprite animations. Manually coding animations takes a lot of time and effort. It's also not very performant. That means the game ends up less juicy than it should be. Why not speed the process up using the domain specific animation language built right into browser?


It turns out CSS is absolutely good enough for a large class of browser based 2d games.

In the end I was able to build and ship a juicy graphical roguelike in about 1.5 months. I used Electron and Cordova to build the Asterogue binaries for desktop and mobile. I used plain old CSS animations for game feel. I saved on code using pure JavaScript with just one library (rot.js). Asterogue is only 2k lines of code which helped a lot with debugging and development speed. Browser based debugging tools are also absolutely fantastic during game development.

I would highly recommend this path to anybody making 2d games. The browser is a killer game engine.


Have fun!