I don't know if I'd be that aggressive about it, but parent is correct that you likely own the IP. An NDA is not a consulting agreement, and it would be very un

I don't know if I'd be that aggressive about it, but parent is correct that you likely own the IP. An NDA is not a consulting agreement, and it would be very unusual for an NDA to assign copyright or declare work product to be a work-for-hire. This gives you a lot of leverage. They want you to give something back because they think you have nothing to take back from them. What you have is way more valuable than the back wages (which are very likely in violation of federal employment law as you've described your situation.) Seriously, talk to a lawyer. Best money you'll ever spend.