It would be dumb on their part as you have all the framework, plans, documentation, etc. to prove that the project is yours. Would destroy any reputation they could build in any medium, adult or not. Not to mention the legal implications of copyright theft and damages. If you have said proof, that would basically end any argument of it being their own.
That being said, if you're afraid of them stealing your work. Have a contract drawn up, basically saying that all work and legal rights belong to ____ and ____ Studios. I, ____ (employee), acknowledge that theft of work will result in _____ and ____ (and so forth). If you're a legit studio and not an online group that'll be non-existent in five months, I highly recommend you go this route. Contact a professional, go over details/concerns, and have him draw up something for you and your 'employees'. It might not come super cheap, but it'll eliminate all of your concerns. That much should be worth it to you. Cover your ass.
If you can't/don't want to do that, back up older prototypes and screenshot any chats that involve agreements/handshake agreements or planning of any sort. It isn't quite foolproof, but it'd be more than enough to at least somewhat prove to the general public that you're the rightful holder of the work. It'd have no legal ground to stand on, though.
