When hire are recruiting and interviewing potential team members they will want to see the game concept and an iteranary where you say pretty much everything about the game... all features that are worth mentioning and how it's different than competitors etc.
The only thing you don't have to show is the GDD.
But with what you show them... sure it can become a very different game but most likely it will be at least of the same genre or the player market that you want.
Means that everyone you show it to could become an unknown competitor if they decline your offer and use the concept + iteranary to make it themselves. And unknown competitors are more dangerous than known competitors.
So is there any way to protect yourself because I doubt most people would sign a contract before getting to read the concept.
Or is it just a risk you must take?