The game doesn't involve anything online.
Let's say it's a huge hit and sells 1,000,000 copies at $1.99 in its first year. That's $2m gross, nets a good chunk less, probably leaving around $1.7m. Since the 10% is taken from gross earnings and not net, that means $200k for our programmer.
Let's say it's NOT a huge hit and sells only 200,000 copies. That's $400k gross, giving the programmer $40k. None of that is bad for a job that took a few weeks tops and some maintenance duty. Add on top of that the potential for some funds derived from a IndieGoGo campaign, and this is not a sad offer.
As for your post script, ideas are everything. Execution is everything only to those who can execute. Ideas, however, are the world if the person who has one can bring people together to make it happen. Besides, you must have an idea in order to bring it to life. Execution is nothing without a seed of inspiration.
Thanks for the luck. No matter what, I'm sure I'll need it -TC