I know some people here disagree with proprietary software but if you eliminated it you would have no games,
OMG Tux Racer!!
so what do you think of semi-open source games like Duke Nukem 3D where the source for the exectable is open but the art and aound is all proprietary?
There is no such thing as "proprietary art," as it doesn't involve code. Art is copyrighted, period. Actually, this method is supported by, of all people, RMS. So it must be reasonable. :p
I like when game engines are open-source (even if later on), because due to the way games work, they usually have to be changed to work on later operating systems. For example, put Quake 1 (original) on a new Windows PC and it would barely work, if at all (unlike non-game DOS apps, which usually are fine).
Perhaps that's not the best example, because I think the old-ish WinQuake and GLQuake by id still work....but what about id's original Linux port? Doesn't work on Linux at all anymore. But because of open-source, the game can still be played - assuming you have the copyrighted art/data. Ditto for playing Doom/Quake on OS X. Everyone wins (gets to play), while the art is still copyrighted and has to be bought - and the same DOS version data works on everything.