"In this article, I introduce some great new games that use the
Quake 3 engine. They're all free, and they all run natively under
Linux.
"First, let's talk about what id Software really did when it
released the engine under the GPL. As Linux users, we're familiar
with terms like, "Free as in speech and free as in beer". For the
record, I have never understood the latter part of that motto. Beer
is rarely free. Nonetheless, the Quake 3 engine is indeed free in
several ways:
"The program is free to download. You don't have to pay for it,
and it's not crippled in any way whatsoever. You can give it to
your friends, for free, and you won't be a pirate. (This is the
"free as in beer" part.)
The program is free to modify, change, repackage and even
sell--provided you include your source code. (This is the "free as
in speech" part.)
The engine is not the whole game. You can't install the program and
expect to frag your little brother in the next room. The graphics,
models, maps and such are not free. If you distribute those things
(from the retail Quake 3 CD), you, in fact, will be a pirate. That
part is not free."