REMIX THIS GAME

REMIX THIS GAME is an experimental game design contest where participants can re-mix and re-cycle my free-software self-published PC game, XONG. XONG is available under permissive licenses allowing remixes and derivative works of the code, graphics, sound effects, and music—even for commercial use. The source code license is the GNU GPL Version 3, and the media is covered by the Creative Commons BY-SA license.

No special software or programming experience are needed—XONG has been packaged up so that you can just download the game and edit the graphics/code/music/sounds in place, and re-start the game to see your changes. Plus, it is available for Windows, Mac OSX, and GNU/Linux, so you can remix it on whichever OS you use, using whatever programs you like.

Registration is now open; sign yourself up here. As the author of XONG, I will choose the winner and three runners up, and do a blog post about each entry with (if you choose) an interview or other info. NOTE: The deadline for submission has been extended to August 10, 2010. There is no real prize other than participation in something new, and possible notoriety for doing something interesting.

See "How do I get started?" below for more details on how to remix the game.

REMIX THIS GAME is part of the 2010 International Lisp Games Expo.

For information relating to Apple developers, please also see Thoughts on iOS games, an opinion essay about the iOS SDK development terms.

XONG is a free, fast-moving procedurally-generated puzzle combat game for Microsoft Windows, Mac OSX, and GNU/Linux. XONG is for one player using a keyboard and mouse. See the XONG page for information, downloads, and links to what people are saying about XONG.

REMIX THIS GAME is inspired by a university experiment I read about, in which a classroom full of mixed programmer and non-programmer students were given a short Breakout clone written in the Processing language, and spent a few hours making various code changes interactively to the game while it ran. A few helpers went around to troubleshoot issues, but almost everyone came up with something cool, with some entries seeming radically unrelated to the original program.

So I invite you to download XONG and:

• Change the rules of player, object, and enemy behavior
• Add new objects and enemies
• Speed it up or slow it down or sync it to a beat
• Resize/redraw the graphics, color schemes, redesign the level generator
• Add a compelling story with non-player characters and heavy exploration
• Implement gravity and change it to a platformer
• Implement a completely different game using the same graphics
• Remix the songs (XM tracker format included for most songs)
• Share your new creations with the world!

XONG has a few bugs and problems, and players have had many suggestions for changes. So you will probably think of things to change about the game. Furthermore, it's relatively simple and small (only 2257 lines of game-specific code.)

I'd like to assemble a gallery and video compilation of people's entries when the contest is over.

Just download XONG for your platform, extract the files, and start editing! All the objects and images are in standard PNG format; the sounds are WAV; the music is OGG Vorbis (with source XM files for many songs.) The source code is distributed among several text files such as player.lisp and enemy.lisp, and also a human-editable resource data file called xong.pak.

As an example from XONG, just below is the complete code for an enemy called the Oscillator. See the documentation in cells.lisp for more detailed information on what each field means—for now, just remember that "cells" are generic game objects, and the "defcell" below defines a new kind of cell with specified properties. The "define-method" forms add actions to cells.

(defcell oscillator 
  (tile :initform "oscillator") 
  (categories :initform '(:actor :obstacle :target :enemy :opaque :oscillator :puck))
  (speed :initform (make-stat :base 3))
  (movement-cost :initform (make-stat :base 20))
  (default-cost :initform (make-stat :base 20))
  (direction :initform (car (one-of '(:south :west))))
  (stepping :initform t)
  (dead :initform nil)
  (name :initform "Oscillator")
  (description :initform 
"These bounce back and forth very quickly, firing muon particles if
the player gets too close."))

(define-method get-nasty oscillator ()
  [damage [get-player *world*] 1])

(define-method loadout oscillator ()
  (incf *enemies*))

(define-method cancel oscillator ()
  (decf *enemies*))

(define-method run oscillator ()
  (if [obstacle-in-direction-p *world* <row> <column> <direction>]
      (setf <direction> (opposite-direction <direction>))
      (progn [move self <direction>]
           (if (and (> 8 [distance-to-player self])
                    [line-of-sight *world* <row> <column> 
                                   [player-row *world*]
                                   [player-column *world*]])
               [fire self [direction-to-player self]]))))

(define-method fire oscillator (direction)
  (let ((muon (clone =muon-particle=)))
    [drop self muon]
    [expend-action-points self 100]
    [impel muon direction] ))

(define-method damage oscillator (points)
  [get-nasty self])

(define-method die oscillator ()
  (unless <dead>
    (decf *enemies*)
    (score 5000)
    [play-sample self "death-alien"]
    [parent>>die self]))
  
(define-method kick oscillator (direction)
  (setf <direction> direction)
  [move self direction])

You can edit and/or replace the game logic and rules with any text editor, and alter the images/sounds with your favorite tools. The game logic is written in the Common Lisp programming language, but because the XONG executable contains an embedded Lisp compiler, restarting the game will cause your code changes to be recompiled when you restart the game. No Lisp experience or special software is required—just make backups, and start tweaking! You can also browse the XONG source online. The wikipedia page on Common Lisp has more than enough information to help you read the game's source code and start making significant changes. Detailed documentation on the underlying XE2 game engine is also available, with specific advice on tools if you decide to tweak heavily or set up a proper Common Lisp development environment. There is also a good cliki page about getting started with Common Lisp.

If the links above and the source comments are not enough, or if you encounter errors, I will be happy to answer questions via email and interactively on IRC. Our community's IRC channel is at irc.freenode.net, and the channel name is #lispgames. I go by the hacker alias "DTO" there. (Actually it's just my initials.)

If you decide to participate, please sign yourself up at the RemixThisGame registration page on Cliki. Please also email me if you decide to give it a shot, so I can keep track of participation and post updates on my blog.

Let the remix begin! Contest entries must be finished by August 10, 2010.

• XONG home page
• Tigpeeps can discuss the game in our Tigsource forums thread