I have a loose hero concept from a while ago that was a forest ranger/fire fighter based on a friend of mine that had a pressure gauge mechanic I really liked. The primary weapon was a hose and secondary fire was a fire extinguisher, both of which were effected by the pressure gauge. Idk how exactly it would work but the hero could change the pressure using one of his abilities and change his playstyle a bit on the fly.
Low Pressure: Shot gun-like primary
Medium Pressure: Mid range obviously.
High Pressure: Sniper primary