Can you people just calm down already. It's been like what 1 or 2 days after this thing has been released and people are already bitching about legal action or damage payments. It's not like we're losing money or whatever, it's euhm free software. There's lot's of open source programs being used for commercial ends. Sure it's nice to be mentioned somewhere but even then there's no obligation to do so. GPL violations can easily be sorted out in time if they just add or remove the necessary files.

On a different note you could of course wonder why ID is still milking their age old dos games, might give the fans something for free after all this time. But okay that's their right to do so.