I think some of the ta spring games might use some old TA content, but yes, the rest seem to be pretty free.
Just to be clear, my picking up on your use of the term free software wasn't a complaint, i thought maybe the UrT people had finally decided to open source it.
I have a lot of trouble finding games that are as enjoyable in the long-term as trem, i do enjoy the occasional round of UrT but can't play it solidly all night like i can trem.
Oh, warzone 2100's quite fun.