Is there a way to show this to people to get opinions without the risk of it being stolen?
look i know you feel pretty unique and all that. but if you spend just a little fraction of your day using the search function on this website you will discover that, actually, no, you are not unique at all.
You're following the very same pattern most people like you follow when they show up with a great idea.. the sooner you'll realize that your idea is worth nothing until somebody (hint.. and that would be YOU ;) ) turns that into a computer software, the better.
Just reading around should clarify you a couple of very important bullet points:
1) Nobody will work for you on your idea
2) If you want somebody to work for you on your idea, get the cash ready
3) No cash? Read point 1
4) If you really want to get your idea going.. learn some basics coding or tool. Get a prototype up, show that you can do stuff.
5) GDD. If you're doing it because you think it's fun then by all means go on and do it. But it won't bring you anything, nobody will read it, let alone steal it.
6) The art of computer gaming is in the execution <- THIS ONE! Doing stuff is the real deal, thinking about stuff is.. nothing really
Failing to understand these things will just make you the Nth new user with a "great idea" that will end up leaving frustrated... seriously, use the search button and save yourself the agony.