I often hear of game breaking abilities being used in games. Stuff like open ended abilities, vague interpretations and clarifications, or even bizarre combination's of rules that create monstrosities. But there is one ability that leaves me scratching my head whenever I hear it being sited as a game breaker. That ability is flying.
I cannot fathom how people have difficulties with flying, unless for some reason the GM only uses ground-bound melee-only brutes with the mental capacity of an angry chihuahua in wide open featureless planes. It's not like you can't have encounters, puzzles, traps, and even entire "dungeons" in the sky.
Which the party members who CAN'T fly have to sit out, because, well, they can't get to them.
Or just have them indoors or under a canopy with a limited ceiling height.
So, flight isn't a problem when it can't be used?
Well, that was obvious.
Heck, even a few bows or a good old fashioned rock can help get things going in the right direction.
If the flying character has range penalties for their weapons, this can work. If not, then they can just use the same weapons, and stay out of range.
Note: Giving flying characters range penalties for their weapons makes perfect sense, because flying means you can't steady yourself. In fact, that's something I'll probably include if I ever make a homebrew that includes flying.
Actually, it could be an elegant solution to allow flight in pre-existing games.
Is it adapting the metagame that leaves people in a fluster?
Changing the game completely, to accommodate something only one player likely wants? It's a big ask.
Are people put off over climbing and jumping skills not being good enough?
Flying=auto-win vs. encounters other people have to invest resources into. Flying needs to get much more expensive.
Are the rules too much of a headache to keep track of?
Depends on the group, but a lot of the time, yes.
Flying during combat takes a lot of extra tracking. Instead of 2d tracking on a battlemap, you now have 3d tracking.
Is getting from point A to point B without having to get tangled up in the bushes some sort of deal breaker?
Meh, overland flight's not that bad. It's bad in some ways (it trivialises challenges for the flying character that are significant for the other characters) but it's very easily limited. And, if you're not using it in fights, doesn't need special measures to control.
Really, why is flying a problem?
Same reason having a character who can walk through walls, and burrow into and out of floors can be a problem.