It looks like most of these games are free software. These are the ones I saw
that weren't:
- Zero Ballistics appears not to be, it mentions only being 'free of charge'.
That's not libre, that's gratis.
- Mega Mario - The content is probably not under a free license, since it
looks to be ripped from Nintendo games.
- Lost Labyrinth - Seems to be a proprietary, commercial game. I can't find
the source code.
- UFO:AI - I can't seem to find the license.
- GameLV - "Warning: Some sound files in data/sound have unknown origin and
unknown licensing and are assumed to be freeware. If you think otherwise
please let us know."
- Arx Libertatis - GPL3 license "does however not include the game data, so
you need to obtain a copy of the original Arx Fatalis or its demo to play Arx
Libertatis."
Please note that I've only scanned through these quickly, so there might be
mistakes. Just be careful and look for the licensing + source code
availability.
Also, here's another free software game:
http://www.redeclipse.net/
