Going about making an iOS game when all you have is a story?

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Hey guys. Hope I'm posting in the right forum here. Basically, I need some advice on how to go about developing for iOS (a JRPG-influences game) when all I have is a great story and gameplay mechanics in mind, and enough passion for both to market the game.

Where do I even start? I know I need someone to code, someone for art, someone for music, etc. The biggest problem is that it seems like most of these people want cash up front, when I can only afford to support my family at the moment. Do people usually work when promised a percentage of sales? Has anyone ever created a game while in the same situation as me and can offer some advice?

iOS developers seem like the unsung heroes in the video game world, so any sort of advice or even just a push in the right direction would be AMAZING. Thanks for your time!