Ever seen an encounter with a flying creature or underwater and wish it just wasn’t there? Ever wonder why? A lot of it has to do with the shift from abstract rules to codified rules.

ABSTRACT vs CODIFIED
Pathfinder 1e, like many RPGs before and after it, abstracts liberally. The classic example; What is a hit point? Some combination of a character’s physical and mental toughness, caginess, and luck that amounts to how many times they can be stabbed. Armour Class is a similar combination of elements, but less abstracted. If your AC is 25, you know what portion of that 25 is your ability to dodge, whereas if you have 100 hit points, you know relatively what amount of that comes from your Constitution and what comes from your class, but that still doesn’t mean much.

Codified vs abstracted rules each have their advantages and disadvantages. When a rule is codified, there is more for a designer to play with. Touch attacks and incorporeal attacks are very similar mechanically, but because they have the codified types of armour they ignore, the big difference between the flavour of both attacks can be explored through subtle mechanics. Likewise, a designer can look at the different types of codified armour bonuses that are less explored. For example, magnifying lenses that ignore size bonuses to AC.

The more codified a rule, however, the harder it is to implement. You don’t just grant temporary bonuses to AC, you grant a type of bonus, which typically don’t stack. The player then has to verify what types of bonuses make up their PC’s total Armour Class to see if they gain the benefit provided. Designers have to be careful too, as there are unwritten rules about the relative power levels of the different types of armour bonuses. Codification can also lead to confusion when the internal logic of the system is not universally agreed upon. For example, if you have multiple magical barriers designed to deflect attacks, only the best one works. A warrior running around with two shields is as easy to hit as the same warrior with one shield. But if you learned to jump out of the way two different ways, you can do both at the same time. I feel the need to clear up that I mean that Dodge bonuses stack for some reason, not that the difference between Dex to AC and Dodge to AC is extremely subtle.

Flip that to our abstract rule, hit points, and you have far less confusion but also far fewer options. Hit points are hit points. You can ask what a hit point is for your entire lifetime in this hobby and never know for sure because the rules intentionally leave it vague. As long as you know how to use it, you don’t need to know how it works. Like driving a car even if you couldn’t pass a basic engineering course. However, too abstract a system and you have to find ways to add to it. Without a solid foundation of codified explanation to hang from, we were left with temporary hit points and hit points you gain temporarily, two different rules both in the Core Rulebook. The latter is presented as the exception, but it is tied to barbarians from 1^st level, earlier than the most common form of standard temporary hit points.

LACK OF CODE
Flying and swimming are problematic because they act like codified rules, but they aren’t coded the same way as the rest of the game. By the above definitions, standard movement is a codified system. You have your speed. It’s measured in 5 ft increments. The world at large is divided into 5 ft squares. The minimum you can move is 5 ft, the max you can move as part of a move action is your speed. That’s 90% of the land movement rules, not even summed up as succinctly as I could. Then there are four other types of movement: burrow, climb, fly, and swim.

Burrowing is uncommon enough that it’s basically treated like teleporting from one land point to another. I can’t think of a single published encounter designed to have multiple burrowing creatures meet and fight while burrowing, but if it came up the burrow rules encompass enough that it can be played out relatively simply.

Conversely, flying and swimming have far more rules, and they are all the wrong rules. Ascending at a 45 degree angle, turning 180 degrees, these are the only instances where in the rules where facing and angles matter, to the benefit of no one. As discussed above, a codified system allows for greater rules expansion. There are few to no feats or spells that interact with the flying vertically or turning around rules. They slow down play and do nothing to add to the fun other than adding a layer of realism to a game that’s OK with characters surviving 100 ft falls.

Meanwhile, rules that would be helpful -like how to play out vertical positioning on the tabletop- are completely absent.

Swimming is similar in that it turns PCs into helpless sinkers unless magic or skill points are invested first. Maybe there’s historical accuracy or realism, but when it creates an “oh no, a water level” feel at the table, too much fun has been sacrificed for the sake of reasons other than fun.

RETROFIT SOLUTION
Fortunately, we don’t need those clunky rules any longer! Even if you are on the fence or decidedly against Pathfinder 2e, the swim and fly rules have been simplified without losing their depth in an easily ported over fashion. Gone are the degrees of difficulty. Here is the fly action, which can be used as a 1e move action with no difficulty:

FLY
Requirements You have a fly Speed.
You move through the air up to your fly Speed. Moving upward (straight up or diagonally) counts as traveling through difficult terrain. You can move straight down 10 feet for every 5 feet of movement you spend. If you fly to the ground, you don’t take falling damage. You can use an action to Fly 0 feet to hover in place. If you’re airborne at the end of your turn and didn’t use a Fly action this round, you fall.

There is no swim action, but the swimming rules and fly action provide the necessary tools to create one:

SWIM
You move through the water up to your half your Speed or up to your Swim speed if you have one. Moving downward (straight down or diagonally) counts as traveling through diffcult terrain. You can move straight up 10 feet for every 5 feet of movement you spend. You can use an action to swim 0 feet to tread in place.

These simplified rules are so much more in line with the granularity of the rest of the 1e system, and much more fitting for the corner case rules that flying and swimming can be. With the above house rule, I never plan to run flying or swimming in 1e the old way.