I'm doing a little research into this. It's based upon EDuke32, which is GPL, so I'm looking for source because apparently the engine has been 'tweaked' for the release. Still not sure if those tweaks are now standard EDuke32 or if it has its' own release tree.
In other news, it's likely to push better networking support for eduke32 which is a little unstable atm.
The lead role is a woman, which is kind of expected in 'current year.' However, it's a pretty solid game, not just a sloppy agenda push. I think we can also expect a 'bikini' patch of some kind in the future, like in the tomb raider days.