Alternatively known as a niche player.

A "rules player" is an individual in a workplace who creates (carves out) their own effective working space and flow based on their workplaces rules, policies, and protocols. A rules player can find multiple ways of completing tasks and could even manipulate loopholes in the workplace to their, or their clients advantage.

The opposite of a rules player is a "rules slave."

When you eat dirt for the first time and leave your family to build a shack in the woods