HotGod ...--i stick to that--...
It's the same as musicians, there are thousands of theme out there.
But there is always on left to discover, no matter if it's about blues, rock, pop or whatever, now and then there is someone coming around that is making the same kind of music but slightly different.
That's the same with making games, there are a lot of them out there, not thousands but maybe millions of them.
So create and make your game, and let others decide...
If they like it you will know, if it sucks...