Game License:

   This game's Content is proprietary and protected by
   national and internation copyright and trademark laws,
   and may not be publicly distributed for free or for profit  
   by anyone but the copyright owner.

GitHub Terms of Service:

   By setting your repositories to be viewed publicly, you agree to allow
   others to view and fork your repositories.

Content(assets) is different from code(source files).

But the license states otherwise:

   "Content" includes but is not limited to the art, sound
   effects, music, and anything covered by national and internation
   copyright and trademark laws. "Content" SPECIFICALLY EXCLUDES all
   source code found within the "flixel-ios" folder of this archive,
   which is distributed under a different license. All other source code
   is considered "Content".

https://github.com/ericjohnson/canabalt-ios/blob/master/GAME...

It looks like both have been put under github.

It's possible to release code and media under more than one license simultaneously.

For such a simple game, Canabalt has some non-obvious tuning: http://blog.semisecretsoftware.com/tuning-canabalt I love such attention to detail.

This is an absolutely inspiring post. I've been thinking about the game mechanics (actual game mechanics :P) for a game I've had in mind for a few years now, and this is huge inspiration. Thanks for linking it. Sadly, I haven't found that many posts like this in the past.

Clarification: The engine is the only thing that is FOSS (i.e. everything in the flixel-ios directory. https://github.com/ericjohnson/canabalt-ios/tree/master/flix... ) The rest is proprietary[1].

[1]: https://github.com/ericjohnson/canabalt-ios/blob/master/GAME...

No; in fact, the game images and sounds are not free, but everything is open source and available for looking at (except the high scores code, which they left out to prevent cheating (explained in the blog post)).

Big difference between open-source and free, at least as you mean it. As the Readme says:

"The code contained within the 'flixel-ios' folder is licensed under the terms of the MIT license."

which allows redistribution. The next paragraph says:

"All other source code remains copyrighted and licensed by Semi Secret Software, LLC under the original terms. See the Game license (filename "GAME_LICENSE.TXT" in this archive) for more details. With the exception of code contained in the 'flixel-ios' folder, you cannot redistribute our source code from the original game. You can use our source code for personal entertainment or education purposes."

So, the code in flixel-ios is FOSS (you can redistribute it,) but the code outside of that directory is source available only (no redistribution.)

Edit: Proprietary software is "...computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, but restricted from other uses, such as modification, further (re)distribution, or reverse engineering.

"Closed-source software, or software distributed without its source code, is proprietary."

I await a fork that lets me, you know, win.

It appears to be an iOS port of the Flixel game library for Flash: http://flixel.org/

That makes sense, since Canabalt was first developed for Flash, then ported to iOS. Adam Saltsman is the author of the Flixel API as well as the Canabalt games.

Interesting, I'd comtemplated writing a similar game using http://anscamobile.com which is lua, but looks and works a lot like actionscript.

Now there will probably be a dozen other similar games though. ;-)