First and foremost, I must stress what I say below is based only on my limited experience. I may not have looked in all the right places or talked to the right people regrettably but that is the reality/pitfalls of being an independent games inventor. I guess I am saying you have to do your research such as it is and maybe talk to people like me who have had a stab at it before going too far in the wrong direction. A good starting point would be to join MeetUp to search for people with similar interests to yourself as there are many local groups of Game App inventors/developers/enthusiasts out there that can help you and give you practical advice.
After coming up with the concept you have to search around for a Games Developer that will build your idea and turn it into a product that can / will sell. A Deal has to be struck with the Games Developer over how their investment is going to be paid. That is, if you pay cash anything from 15K to 25k in today’s money then all is well – I do not know many independent games inventors like me who could afford that figure. So, the alternative is to persuade the Developer that if they do the programming they get a proportion up to half – say of the returns for a fixed period. If any, of course, as it is a business risk but if the Developer is persuaded that your idea is unique and worth their time and effort all well and good. Of course, on first disclosing your idea to any potential Games Developer you must get them to sign a Non-Disclosure document whether or not you go ahead with them. If you do then you have to obtain an agreement as to how the proceeds from the game app will then be divided up.
It may be possible to form a consortium where each puts in a proportion of the costs in some shape or form, if only labour, and the proceeds again distributed according to some agreed formula. It is not something I have yet tried but will in the future I am sure.
It helps significantly too, that during the build with your Developer you take on board any suggested changes to improve your game app as it is a joint enterprise since their advice is based on sound experience. Or at least, you discuss the proposal and find a common ground to incorporate these beneficial changes to the game or agree to not use it for reasons you both know. You cannot think of everything when you first come up with a game app you will find it evolves between you and the Developer into something better than you ever imagined. I cannot praise RagTag enough for staying with me on my journey and getting that end-product finished to a high standard. I hope to reward their commitment too and give the playing public a lot of fun and a challenge and the chance to learn at the same time!