Sometimes I come up with weird ideas. Sometimes those ideas happen when I'm on the second throne, sometimes they happen when I'm reading totally non-related things.
r_b_bergstrom of the blog Transitive Property of Gaming wrote about WFRP 3e today and I was wandering through that post, having made a side trip to Delta's blog to print out the Target 20 system because I love it and must have it and have been using it already in my head...
... so r_b writes: "So I was pleasantly surprised that the game uses very abstract positioning rules, with the assumption that a melee is "like a rugby scrum" with everyone in constant movement. If you're part of the melee, you're engaged with everyone. If you _need_ to get somewhere, you just do, but it costs you a few fatigue points. This is a completely different paradigm, and it feels fresh and innovative."
Now a few months back, I played 3:16, a player narrative type of game that had 3 rangers. Close, Near and Far. It was easy to tell who the D&D'ers were because they wanted to operate on the range based on a number that gives a discrete amount. Once they/we wrapped our heads around what the various ranges really meant in terms of narration vs. actual mechanics, things worked better.
One of the games I'm running is an online Wave game in my Dark Ages world. In that setting, ranges can get fiddly as we're not dealing with minis or such. It occurs to me that the abstract 3:16 type of range could be laid on top of simple combat systems, such as OD&D/AD&D.
If you're at Close range, you're in melee. Mechanics such as flanking, back-stabs, rear attacks, 2nd row spears don't matter in terms of range, but in terms of spending time/abilities to do so. Close could be 10' or a circle of 30' or whatever - it's more about going face to face with your enemy.
If you're at Near or Far, you're limited to missile fire. Near weapons are hurled or smaller missile weapons. If you're at Far, you're doing missile fire with Far weapons (long bows, firearms, crossbows) or adding +2 to Near range missile weapons.
If you're Out of Combat, you've fled the combat zone, whatever that is.
This doesn't take out determining who attacks who, and you can still deal with spell-casters being in melee.
 To flank or rear-attack, you would indicate an opponent (or just say you wish to try to do so on someone - if the DM rules that there's the possibility, say in a rough terrain area or the number of participants would mean a type of scrum, then I'd allow it, if it was a narrow dungeon corridor or very military based opponents with lines and shield walls, I'd disallow it - I would rule it would take a round to set up the flank/rear attack, next round's attack gets the bonus. Same with monsters. Back attacks require the thief to hide in shadows or move silently, whichever the DM ruled appropriate... then the next round, they get the back-attack.
I don't really use inches, grids or the like in my combats, and indicating abstract ranges can remove the argument of who is in the range of something exploding - if you're at Close and a spell is flung into the melee, say a Fireball, everyone at Close gets nailed. DMs can still rule on effects (I'll aim the sleep spell so that it affects the monsters only - DM makes a gut check if that sounds plausible... if the players have been describing a general scrum... PCs might be zzz'ing.)
I wonder if I'll lose my OSR card for this. It's an interesting thought exercise, nonetheless.