Not a lawyer here, but here's what I've managed to figure out:
TL;DR: the software licenses don't seem to stop anybody to use ETR in a money-making situation, as long as the source is accessible (a requirement only for GPL).
As far as I know, GPL is not incompatible at all with making money.
For example, if you distribute copies of such a program, whether
gratis or for a fee
, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
This is, as far as GPL(v2) goes, we could even build ETR machines and sell them and it would be ok as long as end users had access to the source code (which could be done by including the source code in the RPi memory card or extremetuxracer.com when it's finally up again).
Other things that may need license:
* OpenGL: From what I could read on their page
, there's no license needed for developing OpenGL software; only for developing video card drivers.
* SDL: 1.2 and older: LGPL. 2.0 and newer: zlib license
, which says "Permission is granted to anyone to use this software for any purpose, including commercial applications"
* Freetype: "FreeType
comes with two licenses from which you can choose the one which fits your needs best: The FreeType License
and GPLv2."About the Raspberry Pi
(and what I've asked on their IRC):
* It's OK to resell RPis, or build a machine based on it that makes money
* It's NOT OK to call it "The RaspberryPi Arcade" or put a RaspberryPi logo on it. (It seems ok to indicate that it's "Powered by RaspberryPi", though)
There may also be license issues regarding royalties in media formats (e.g. if it uses MP3, which afaik doesn't). And no idea if there are laws forbiding people to make money without a license, regardless on how that money is made, and which taxes may apply.