A downloadable game engine for Windows, macOS, and Linux

Buy Now$47.31 USD or more

Updated Aug 15, 2020, Total releases (so far): 46
Creation Apr 19, 2019
Rating (30)
Tags2DdragonrubyGame engineModdableruby

DragonRuby Game Toolkit is a professional grade (yet beginner friendly) 2D game engine. It's tiny (~3MB), fast as hell, and cross-platform (including consoles).

Free Unrestricted License

You are eligible for a free license if any of the following items pertain to you:

  • Your income is below $2000 (USD) per month.
  • You are under 18 years of age.
  • You are a student of any type: traditional public school, home schooling, college, bootcamp, or online.
  • You are a teacher, mentor, or parent who wants to teach a kid how to code.
  • You work/worked in public service or at a charitable organization: for example public office, army, or any 501(c)(3) organization.

Just contact Amir at ar@amirrajan.net with a short explanation of your current situation and he'll set you up. No questions asked.  

So what's so great about DragonRuby Game Toolkit?

  • Dirt simple apis capable of creating complex 2D games.
  • Fast as hell. Powered by highly optimized C code written by Ryan C. Gordon, the creator of SDL (a library that powers every commercial game engine in the world).
  • Battle tested by Amir Rajan, a critically acclaimed indie game dev.
  • Tiny. Like really tiny. The entire engine is a few megabytes.
  • Hot loaded, realtime coding, optimized to provide constant feedback to the dev. Productive and an absolute joy to use.
  • Turn key builds for Windows, MacOS, and Linux with seamless publishing to Itch.io.
  • Cross platform: PC, Mac, Linux, iOS, Android, Nintendo Switch, XBOX One, and PS4 (mobile and console compilation requires a business entity, NDA verification, and a Professional GTK License, contact us).

Ryan put together a 5-minute intro to DragonRuby GTK, to give you a whirlwind tour of the big ideas:

This is a tech demo sample app that ships with DragonRuby. The GTK's entire API is displayed here.

The developers behind DragonRuby GTK.

This is Ryan C. Gordon (Wikipedia), he is one of the juggernauts behind Simple DirectMedia Layer (Wikipedia). 

Ya know... 


that low level library that powers literally every commercial game engine out there

He's also worked on porting a number of games to Linux and Mac OS: such as Braid, Super Meat Boy, Dear Esther, and LIMBO.

And this is Amir Rajan, he is an indie game dev with titles on iOS, Android, desktop, and Nintendo Switch... amassing 4 million downloads and counting (Nintendo, Kill Screen, The New Yorker). And yes, all these games are built with the DragonRuby Runtime.

Both of these guys hate the complexity of today's engines. And as luck would have it, their paths ended up crossing. After six months and 50,000 lines of DragonRuby Runtime enhancements, Ryan and Amir now have a live/hot loadable, cruft-free, productive game engine that can target... well... any gaming device you can think of. 

Hello World is one file, three lines.

This is all you need to create a game. One file. One method called tick. Here we render the current step value as a label:

def tick args
  args.outputs.labels << [100, 100, args.state.tick_count]

That's it. If you know how to use the array datatype in any language, you know how to use the DragonRuby Game Toolkit. Here's the proof right here, play around with the engine in your browser.

Output: Six rendering primitives is all you need.

Here are the six draw primitives you need to know: solids, sprites, labels, lines, borders, and sounds. Here is how you use them:

def tick args  
  # draw a blue square that's half way faded out
  args.outputs.solids << [100, 100, 50, 50, 0, 0, 255, 128]
  # draw a red label  
  args.outputs.labels << [100, 100, "This is a label.", 255, 0, 0]
  # draw a sprite turned 45 degrees and half way faded out
  args.outputs.sprites << [200, 200, 50, 50, 'ninja.png', 45, 128]
  # draw a diagonal green line from bottom left to top right
  args.outputs.lines << [0, 0, 1280, 720, 0, 255, 0]
  # draw a black border (unfilled square)
  args.outputs.borders << [100, 100, 50, 50, 0, 0, 0, 255]
  # play a sound every second
  args.outputs.sounds << "ping.wav" if args.state.tick_count % 60 == 0

That's it. You now know the entire render api for DragonRuby GTK.

Here's a more complicated example. This is how you create a night time scene, with a title, and a ninja:

  1. solids: A black background, and two hundred stars made of tiny squares.
  2. labels: Display some smokey-white text.
  3. sounds: Play a sound when the game starts up.
  4. sprites: Render a sprite on the screen.
  5. lines: Draw a line representing the floor
  6. borders: Frame the entire scene with a white border.
def tick args
  # destructure args into local variables
  state, outputs, grid = args.state, args.outputs, args.grid
  # set some default values for the game
  state.colors.background ||= [0, 0, 0]
  state.colors.star       ||= [128, 200, 255]
  state.colors.text       ||= [200, 200, 200]
  state.colors.landmarks  ||= [255, 255, 255]
  state.night             ||= [grid.rect, state.colors.background]
  state.stars             ||= 200.map do
    [rand * grid.w,
     rand * grid.h,
     rand * 2 + 2,
     rand * 2 + 2,
  # start up some background music
  outputs.sounds  << "opening_fx.wav" if state.tick_count == 0
  # render the background and stars
  outputs.solids  << state.night
  outputs.solids  << state.stars
  # set a title for the game
  outputs.labels  << [grid.left + 50, grid.top  - 50, 
                      "Ninja Game", state.colors.text]
  # set a sprite
  outputs.sprites << [50, 50, 50, 50, 'ninja.png']
  # create a line that represents the ground
  outputs.lines   << [grid.left, 
                      grid.bottom + 50, 
                      grid.bottom + 50, 
  # create a border to frame the game
  outputs.borders << [grid.left + 1,
                      grid.bottom + 1, 
                      grid.right - 1, 
                      grid.top - 1, 

Input: Controllers, Mouse, and Keyboard.

This is how you move a sprite using your gamepad:

args.state.ninja.x ||= 100
args.outputs.sprites << [args.state.ninja.x, 300,
                         50, 50,
if args.inputs.controller_one.key_held.right
  args.state.ninja.x += 10
elsif args.inputs.controller_one.key_held.left
  args.state.ninja.x -= 10

This is how you move a sprite using your mouse:

args.state.ninja.x ||= 100
args.outputs.sprites << [
if args.inputs.mouse.click  
  args.state.ninja.x = args.inputs.mouse.click.point.x

This is how you move a sprite using your keyboard:

args.state.ninja.x ||= 100
args.outputs.sprites << [args.state.ninja.x, 300, 50, 50, 
if args.inputs.keyboard.key_held.right
  args.state.ninja.x += 10
elsif args.inputs.keyboard.key_held.left
  args.state.ninja.x -= 10

Game State: Entities and Collision.

Randomly create 500 ninjas on the screen. Create a lookup table that contains the alpha property of ninjas that have collided. Present all ninjas with their alpha properties set.

def tick args
  # destructure args into local variables
  grid, state, outputs = args.grid, args.state, args.outputs
  # use Game Toolkit's built in helper methods to create
  # adhoc entities
  state.ninjas ||= 500.map do
                    { rect: [grid.w.-(50) * rand,
                             grid.h.-(50) * rand,
                             50] })
  # use Ruby's powerful apis to determine collision
  state.collisions ||= state.ninja
                            .reject { |n, n2| n == n2 }
                            .find_all { |n, n2| n.rect.intersects_rect?(n2.rect) }
                            .map { |n, _| [n.entity_id, 128] }
  #render everything to the screen
  outputs.sprites << state.ninjas.map do |n|
    [n.rect, 'dragonruby.png', 0,
     state.collisions[n.entity_id] || 255]

Support for aspiring game devs.

Need a bit more guidance in learning how to program? We're starting to build training videos for DragonRuby GTK. Check those out at dragonruby.school.

Updated 12 days ago
PlatformsWindows, macOS, Linux
Tags2D, dragonruby, Game engine, Moddable, ruby


Buy Now$47.31 USD or more

In order to download this game engine you must purchase it at or above the minimum price of $47.31 USD. You will get access to the following files:

dragonruby-gtk-macos.zip 54 MB
Version 68
dragonruby-gtk-linux-amd64.zip 52 MB
Version 68
dragonruby-gtk-linux-raspberrypi.zip 52 MB
Version 60
dragonruby-gtk-windows-amd64.zip 53 MB
Version 68

Development log