Forums of the Megaverse®

So, what new content was supposed to be in TMNT & More Strangeness 2nd Ed.?

The description in the Summer 1999 Palladium catalog mentions:
'New text includes a look at the mutant underground and mutants as heroes.'

Does the HU sourcebook Mutant Underground pick up this material, or is that completely new?
Has the planned new material for TMNT 2nd Ed. just been lost in the ether? Or have we seen it published in Mutant Underground or After the Bomb?

sorry to be the one who has to tell you, but TMNT 2nd Ed was canceled a while ago.

Presumably any new rules on the game mechanics of mutant animals are in After the Bomb 2e. Everything else is likely dead and buried, never to see the light of day (except perhaps in future AtB supplements).