Not extensively, but we have had a couple of instances, especially dealing with water. Not quite as many times when dealing with up in the air, but that's about to change sooner or later.

I played a succubus ranger in one game, i constantly did battle in three dimensional combat. There was this one time we were facin off against a demonic vampire and i was engaged in combat with her in the air and i was dippin and divin to keep her from hittin me... and then i got hit when i was 120 ft up and i just died on impact.

That sucks man.

brought a kobold dragon fire adept with improved flight and air heritage into a lv 7 campaign and destroyed it in one session since the enemy empire wasn't prepared for a 150hp regenerating, AC 35 tiny dragon with a 250 foot fly speed

I'm pondering running a campaign later in a primarily underwater setting, over the internet. The best solution for maps I've found is a program called MagicaVoxel. Has anyone had anything better?

Roll20 is really good in general, though it doesn't do 3d; you can put notations next to each character to show elevation, though. There might be a better way to do it than following tokens around with textboxes, but I don't know it. :/

I'm pondering running a campaign later in a primarily underwater setting, over the internet. The best solution for maps I've found is a program called MagicaVoxel. Has anyone had anything better?

Most of the time when combat went 3D, we'd either fudge it to treat it more like 2D or go for more abstract combat rules, which accomplished much the same thing. It helps a little that if you're the only flyer (or at least there aren't many) it makes you a big target.

Oh, and being me, that's of course GURPS rules. ;)

Does underwater hockey count?

... which reminds me, if Kuroobi is referring to the bends, that won't happen unless you're breathing compressed air underwater. Think SCUBA.

No, the human body, especially any part with air in, really doesn't react well to quick changes in pressure. Even scuba divers descend and rise slowly to get their bodies used to it and still can get intense migraines and bleeding orifices as the air in their sinuses ect. contracts/expands. Try diving down to the bottom of just a 3m pool and see how your head feels

You're right about the bends, but like KastorUK mentioned, there's a whole world of damage that can be caused to the human body by rapad pressure change: https://en.wikipedia.org/wiki/Barotrauma

Had a low mid-level Fighter/Mage once make a pair of winged boots... melee, ranged, and area effect combat in mid air against a harpy shamaness was probably the most epic fight of the campaign - to the point where both the other harpies, and my ground bound allies, just stopped to watch.

...actually I did have some exalted characters with maxed out athletics. Not necessarily overloaded with athletics charms, but even with just stunting and the basic assumptions of the game (and playing it freeform) we did a lot of wallrunning, jumping, swinging about and somersaults. Having a guy who could shoot magical ropes attached to his arrows helped.

I'm not sure if it counts, but I also had a Chaos Space Marine with a jump pack in a Black Crusade setting once.

My brick of a super began leaping around in our Nessacary Evil game, and sadly was the first to bring in 3d combat.

and we had a flying force control adept in the part. the undead super mage was more of a support player and blew things up from afar.

still i enjoyed zangeif'ing enemies into each other and dusting living beings from sheer damage. YAY FALLING DAMAGE IMMUNITY!

....Very. Very often. On the Pokemon Tabletop United system in particular, where both Players and the GM brought in Flyers and few instances of Pokemon going underground or underwater. Luckily, the group I am in uses the notations on the tokens to tell whose elevation is at, as well as the GM had early on put down the limitation how many feet in the air we're allow to go up max.

So, that kinda limits how big the three spatial dimension combat. Even more so, considering that the attack range on PTU is more or less set compared to Pathfinder.

There was this one time I was in an Evil Campaign. The general plot was that the party were members of a cult of Tiamat in a world where Cromatic Dragons were extinct And tiamat tasked us to bring them back by turning us into dragons.

my Character was the White Dragon of the group giving me Burrow and Flight and our 1st task was to go to a nearby lichs fortress and find a magic mcguffen he had that we needed. Said fortress had a fairly large number of undead minions patrolling the grounds.. so while the rest of the party waited I burrowed underneath the entire fortress and popped up in the lich's tent,flooding it and the area around it with mist. later that fight while the others were taking out the minions with there breath weapons.. I decided the best course of action was to grapple him and take him for a ride high into the air... he did not survive the fall.

One of the gaming groups I was in had some pretty cool and powerful characters one of them was a barbarian with herculean str thanks to various magical tattoos. During one session we were attacked by a water elemental and he ended up wrestling it under water and winning.

once played a pickup-type session where we had a dwarf warrior who had a magic belt that let him teleport (think it was Houseruled or something)
the catch was each time he used it he had to make a roll with penalties or bonuses given the situation.
A fail could mean either the belt didn't work or sent him off target.
he tried to use it while we were in combat- against a Drake? (smallish dragon)
he botched the first roll and then had to roll again to determine how far off target.
He meant to teleport onto the roof a nearby builing to catch the drake off guard. instead he winds up in mid-air.. right in front of it.
Fire Breath+ falling damage= dwarf comet chunky salsa.

once played a pickup-type session where we had a dwarf warrior who had a magic belt that let him teleport (think it was Houseruled or something)
the catch was each time he used it he had to make a roll with penalties or bonuses given the situation.
A fail could mean either the belt didn't work or sent him off target.
he tried to use it while we were in combat- against a Drake? (smallish dragon)
he botched the first roll and then had to roll again to determine how far off target.
He meant to teleport onto the roof a nearby builing to catch the drake off guard. instead he winds up in mid-air.. right in front of it.
Fire Breath+ falling damage= dwarf comet chunky salsa.