As all old-fashioned games fans should know source code of Hexen and Heretic were released as open source software somewhere in 2000 year.
There was an idea on Brainstorm about compiling it and putting it into repository (http://brainstorm.ubuntu.com/idea/12913/),
but many people commented the original game IWAD file, which is needed to play, wasn't released, so there is no point compiling this game.
I worked quite a lot on WAD's and IWAD's and I am familiar with this file format. Let me present what the IWAD contain:
-weapon data (images/animations)
-monsters data (images/some weird stuff like behavior)
The rest of the game, I mean phisics and graphic alghoritms, and maybe some more features are contained in the game executable itsels, so this not require a WAD file.
== What about creating our own IWAD?
What about making IWAD, that would allow everyone to freely play the legendary games in new style, but with old climate?
The software needed to making IWAD is freely available, and there is no problem making fake IWAD. We could totally change the game, new monsters, maps, but keeping the original climate. Making a totally new game based on the old Heretic/Hexen needs just some time.
I think many people would volunteer in this project, as it requires work from many different categories: graphics (weapons, monsters, textures), sound (music, effects), mapping. There are actually no programmers needed, as we have ready game engine. Ubuntu community should have no problem finding right people.
I think it would be awesome to reborn the legend! I know there are so many old FPS fans, there are many people complaining about the nubmer of nice games in Ubuntu... Hexen/Heretic are small, effective, nice-looking 'old 3d' games, I'm sure many players would hook on them!