I recall in 2005 a poster here at EN World worked with me to whip up a grid-free RPG combat system (named Dungeons or Dragons) which had Fields for mass combat, Theaters within them for distant ranged combat or high-speed units like dragons or cavalry, Arenas for medium ranged combat and average mobility units like infantry, Stages for little spotlight areas where melee combatants would fight, and finally Loci for ultra-specific spots that only one character could occupy.
IIRC we had a sort of PF2-esque action economy where you had two fungible actions, and it cost one action to move between Stages in the same Arena (or to leave melee reach but stay in the same Arena), or two actions to move between Arenas in the same field (or to get to long range but stay in the same Theater), and usually if you wanted to change Theater you had to use a 'running away' skill challenge.
I thought I was rather clever at the time for coming up with those. But yeah, they'd been around in non-D&D-derived games for a while.