Do You Start With a Mechanical Idea?

Sometimes a game starts with a mechanical idea. Sometimes it starts with a world that i'm trying to build off of, or build from. There are times where i i look at a game and i i think, ok, this would be interesting, but we already have a couple of games like this. I'd rather focus on something else. In the end, it comes down to the fun, whether it starts with an idea for a new game,. A thematic idea, w trying to make the game as fun as possible. It's just figuring out if, ah, the game is is capturing the experience that i'm going for.