Source: https://github.com/jakesgordon/javascript-delta
Original host: https://jakesgordon.com/games/delta/
Editorial image: https://jakesgordon.com/writing/javascript-delta/delta1.jpg
Credit: jakesgordon and project contributors.
Checked: 2026-10-27.
This site links to the original game; no game code or audio is republished. Artwork may have terms separate from code.

Repository license notice:
Copyright (c) 2014, 2015, 2016 Jake Gordon and contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.


README / artwork and usage context:
Javascript Delta
=================

This is a small weekend homage to the classic c64 shoot-em-up "Delta".

 * [Read more](https://jakesgordon.com/writing/javascript-delta/)

TODO
====

 - POWER UPS
   - speed
   - fire rate
   - fire multiple
   - fire up/down/back
   - shield

 - MORE ALIEN VARIETY:
   - rotate around a queen alien
   - pillars with gaps to fly through
   - boss aliens
   - split/multiple waves (e.g. 2 or more independent waves at same time)
   - ddx/ddy accelerating (hyperbolic and elliptical motion)
   - give aliens customizable health so they might take multiple shots before dying
   - give aliens customizable shot rate

 - MORE GRAPHICS
   - alien graphics
   - bullet graphics
   - rock/border graphics
   - title screen graphics

 - CLEANUP and MISC
   - clean up the hideous N^2 collision detection code
   - use a little PUB/SUB event handling for simpler code
   - "are you sure" confirmation on quit
   - high scores
   - performance (avoid garbage, optimize rendering)


DEVELOPMENT
===========

The game is 100% client side javascript and css. It should run when served up by any web server.

Any changes to the following files will be reflected immediately on refresh of the browser

  - js/delta.js
  - css/delta.css
  - images/
  - levels/

However, if you modify the js/game/ or js/vendor/ javascript files, the unified versions need to be regenerated:

    js/vendor.js        # the unified 3rd party vendor scripts (fpsmeter, state-machine, etc)
    js/game.js          # the unified general purpose game engine

If you have the Ruby language available, Rake tasks can be used to auto generate these unified files:

    rake assets:create   # re-create unified javascript/css asset files on demand
    rake assets:server   # run a simple rack server that automatically regenerates the unified files when the underlying source is modified

Attributions
============

All sounds effects are CC licensed from freesound.org

 - [shoot](http://www.freesound.org/people/bubaproducer/sounds/151011/)
 - [explode](http://www.freesound.org/people/Nbs%20Dark/sounds/94185/)

Music is (respectfully) borrowed from [Rob Hubbard's](http://en.wikipedia.org/wiki/Rob_Hubbard)
original because it's ABSOLUTELY FANTASTIC! 

 - [High Voltage SID Collection](http://www.hvsc.de/)

All graphics are (respectfully) ripped from original R-Type arcade games by

 - [http://www.retrogamezone.co.uk/rtype.htm](http://www.retrogamezone.co.uk/rtype.htm)

License
=======

[MIT](http://en.wikipedia.org/wiki/MIT_License) license.