To be honest, any basic structure of a game can work if its designed and implemented well.
For example, how about a sci-fi and fantasy mix up with epic scaled wars? Warhammer 40k
Steampunk under water city with scuba diver who can use magic? Bioshock?
Living creatures used in the destruction of other living creatures? Angry birds.
What you need is to find what ever way works for you, to flush out a story or purpose, whats the end goal in the game, then how do you get there, what obstetrical will you face? What tools/skills do you have to overcome these, how do you obtain them?