This, in a nutshell, is the biggest problem with the solo game/app developer. Any concept simple enough for one person to implement has been done to death by hundreds of other people already. So how do you differentiate?
Marketing.
>> 2) marketing is everything.
> no. no it's not.
Unfortunately, it is. See, it doesn't matter how novel and awesome (aka differentiated) your product is, you still have to sell it. In order to sell the product, you have to have the right product. This is why traditional marketing includes product development (look up the 5 Ps of marketing). Marketing as a function can tell you where your users are and what they're looking for. Then you design your product based on that, and find the optimal way to sell that product to your target users. The pricing/promotion piece (or what people usually think of as "marketing") comes at the end.
Promotion in and of itself is not a differentiation strategy unless you have deep pockets. But promotion is absolutely required to launch a successful product: I don't care how differentiated your product is, if your users don't know about it, it might as well not exist at all.
> 3) it's a lottery.
It pretty much is a lottery at this point. Any game with a unique concept that is doable by a single person is pretty much immediately copied 10 times over by a Chinese/Indian sweatshop. Why develop your own new game when you can copy someone else's? Throw 10 copies of the app up with slightly different graphics in the hopes that one of them catches fire. Good luck trying to sue a foreign company as an independent developer; even if you win they'll never pay up.
App development has become a portfolio game specifically to deal with the randomness. If you view the costs for developing a product as encompassing both SW development costs AND marketing costs, the marketing costs would easily outstrip the development costs. Underperforming apps are unceremoniously killed, and more marketing dollars pumped into the ones that start succeeding.
It's hard to play that game as an indie developer, which is why we've seen so many of these posts pop up recently. People were sold on this vision of an egalitarian, meritocratic app economy and it's just not true. In a maturing market like mobile gaming, the one who shouts the loudest commands the most attention. For an indie dev with no capital, that can be really hard to do.