Hey there, my name is Simon, and I've been developing console games for the past 14 years.
About 6 months ago I quit and started making games for iOS and Android full-time. My first indie effort is Sun Stones (available now! Awesome! And Free!) and I'm really proud of how well that project came together.
However, that's not what I'm here for. I have a few months of support for Sun Stones lined up, but it's time to also start brainstorming some ideas in parallel for my next project. I'll outline how I work briefly, so you know how to best help me brainstorm:
1 - I like to identify an aesthetic identity for the game. This is an idea, culture, theme, etc that permeates the whole visual and auditory affect of the game. Sun Stones uses Hopi glyphs & flutes for an aesthetic identity. This ideally has NOTHING to do with the mechanics of the game - it's just something cool and distinctive which gives people an easy way to talk about the game.
2 - I decide on one simple action, which players will be doing moment-to-moment. For example Jetpack Joyride is "tapping to fly up and down" and Angry Birds is "pulling back a sligshot." Bejeweled is "touching to swap gems" and Flight Control is "drawing smooth curves." This doesn't have to have anything to do with a game idea, or the answer to #1. But whatever people are doing a lot of requires some serious iteration, so this often comes first for me.
3 - This is just a strategic question - but I'm not sure whether I should be building on the modest financial success of Sun Stones by appealing to the same demographic, or if I should be stretching my wings to make something totally different? Building long-term fanbase is more important to me than any individual game.
4 - If anyone has specific contributions they might want to make for the next project (art, audio, marketing, wads of cash?) feel free to contact me directly!