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Alternately, find the entry point to a chaotic interaction and design rules around structured exploration of that interaction. Then adjust into a legible, well-paced gameplay loop to taste.

That's how you can come up with a game like pinball(ball-on-plane physics), Tetris(tetronimos), or Sokoban(box-pushing on the grid) - interesting interactions with a lot of inherent complexity, and core loops that are immensely mundane in description. This strategy applies as well to conventional narrative: Set up some absolute rules of the world, then start simulating what happens.

Loop-based workflows are useful in terms of establishing the "economic model" and fleshing out the core concept, but they've only really been in the practiced parlance since the rise of MMOs and subsequently popularized through reduction to the simple compulsion loops that now drive most mobile games. They really don't deserve the central role they've been given lately.