Diagonal Movement Through / Around Creatures and Walls

For the longest time, I've run PF2 like it was PF1 movement rules where you couldn't move diagonally if a corner was in the way but could move diagonally when creatures were involved.

Now someone has me questioning this and I'm struggling to find clear rules. So, let's reference this diagram where a PC (or NPC) is trying to move from S(tart) to F(inish).

1, can the PC move diagonally between W1 and W2? I think everyone agrees the answer is no.

2, if W2 is removed, can the PC move diagonally from S to F or do they need to go through the W2 square?

3, can the PC move diagonally between C1 and C2? Or is it blocked/would it require a tumble through check?

4, if C2 is removed, can the PC move diagonally from S to F or do they need to go through the C2 square (or tumble through the C1 square)?

I am looking for actual rules references if possible to settle this disagreement.

I don't think there is or can ever be a definite rules-based answer to at least the first half of this question. I can only provide my own insights.

1, This is an incomplete question. Are those wall segments connected or do they form two sides of a corridor/choke point? How thin or thick? PF2e isn't an ascii graphics dungeon crawler (unless you actively make it one I suppose) where walls are delineated as a binary yes/no per tile with unshakable laws governing them, it depends on the actual properties of the wall(s) we're discussing in the fictional space the tokens are inhabiting. If the walls are connected I would obviously disallow diagonal movement through them as presented in the image. In any other scenario I might do anything from only allowing smaller PCs/minions to requiring a Squeeze check to just straight up allowing movement from S to F.

2, Similarly incomplete question, is it a pillar that takes up most but not all of the space of the tile or a hard corner that precisely lines up with the tile's boundary? The nuances of an (imaginary) physical space can't be captured by one-size-fits-all laws and I don't think they should. Still, in a single wall scenario I would personally by and large allow a PC to make a diagonal movement from S to F.

3 & 4, I think easier to handle, there's nothing stating that you can't move around/between creatures like that, I would not require a Tumble Through check to get from S to F in either case and allow direct diagonal movement.

If anyone does have rules citations to back up or debunk these rulings do post them

For the longest time, I've run PF2 like it was PF1 movement rules where you couldn't move diagonally if a corner was in the way but could move diagonally when creatures were involved.

Now someone has me questioning this and I'm struggling to find clear rules. So, let's reference this diagram where a PC (or NPC) is trying to move from S(tart) to F(inish).

1, can the PC move diagonally between W1 and W2? I think everyone agrees the answer is no.

2, if W2 is removed, can the PC move diagonally from S to F or do they need to go through the W2 square?

3, can the PC move diagonally between C1 and C2? Or is it blocked/would it require a tumble through check?

4, if C2 is removed, can the PC move diagonally from S to F or do they need to go through the C2 square (or tumble through the C1 square)?

I am looking for actual rules references if possible to settle this disagreement.

Depends if you as GM considers that have enough space. Battle maps are very good abstractions to help the characters to get a very good vision about position of all things and characters but they aren't 100% representative. For example if a character is blocking a door, that usually is small than 5 feet large, you can rule that diagonal is impossible without Tumble Through. But if you rule that have enough space (like having the wall just in one side) you probably should allow the creature to move.

Remember that even having clear rules it's up to you as GM to give the final decision about everything involving the scenario because it is your creation and only you know and rules all the details. That said try to avoid to go to far from the expected RAW rules to prevent unexpected frustrations to your players and try to be transparent about these situations with antecedence if possible.

1, This is an incomplete question. Are those wall segments connected or do they form two sides of a corridor/choke point?

Assume both grid squares are 100% made of stone or iron or something.

3 & 4, I think easier to handle, there's nothing stating that you can't move around/between creatures like that, I would not require a Tumble Through check to get from S to F in either case and allow direct diagonal movement.

But is there something stating you can?

In PF1 we had this:

"When measuring distance, the first diagonal counts as 1 square, the second counts as 2 squares, the third counts as 1, the fourth as 2, and so on.

You can’t move diagonally past a corner (even by taking a 5-foot step). You can move diagonally past a creature, even an opponent.

You can also move diagonally past other impassable obstacles, such as pits."

That said try to avoid to go to far from the expected RAW rules to prevent unexpected frustrations to your players and try to be transparent about these situations with antecedence if possible.

That's my concern here, I've never run it that way or seen it run that way but now a DM is claiming that and I've realized the rule might in fact not be crystal clear. But it's going to be weird for me to try to remember this DM is handling movement differently.

There simply isnt a written rule that I know of that deals with this scenario, I've always ran it that you cant go diagonally trough hard corners as that would mean you collide with the wall or at some point step into each of the 3 remaining squares during the movement. Any line you make would collide at the actual corner.

Creatures are different in that they do not take up the entirety of their occupied space so you can move diagonally trough such corners.

If the blocking or impassible terrain extends to the corner then it makes sense that you cannot move diagonally trough that corner. Similar to how you can have standard cover from a creature if the line between the two tokens passes trough such a corner, As Shown in this in-book example

I absolutely will block both diagonal movements. Provided there's no actual space in the first case and allowing (of course) tumble through in the second. In the second case there's absolutely no difference between diagonal and linear, side to side arrangement of creatures in fiction. So there won't be such difference in the ruling. I don't care about how this looks on the square grid. If it were hexagonal grid, there wouldn't even be a question. So the answer will be same.
As for half-filled diagonals, no corner going for full square filling obstacles is a reasonable (and relatively insignificant) ruling. If it's a creature or not fully filling obstacle, then it's ok to go diagonally (and no need to tumble through).

I feel like having the rules not include an analog to the PF1 text mentioned upthread is both intentional, and useful for the PF2 rules.

Sometimes it makes perfect sense to the people playing the game in the particular scenario they are in that a diagonal move be possible, or not possible, and having a rule call out that one of those things is actually incorrect means the rules are getting in the way.

So the current situation of it being up to the groups perspective and preferences is just skipping the part where the rule gets applied inconsistently because of reasoning like "yeah, you can't move through a corner, but this is a really open kind of corner so actually you can"

I absolutely will block both diagonal movements. Provided there's no actual space in the first case and allowing (of course) tumble through in the second.

Which creature(s) is/are getting tumbled through?

Also, if there's an enemy fighter with a non-reach weapon to the bottom left (SW) of C1 or upper right (NE) of C2, which (or both) gets an AoO?

Errenor wrote:

I absolutely will block both diagonal movements. Provided there's no actual space in the first case and allowing (of course) tumble through in the second.

Which creature(s) is/are getting tumbled through?

Also, if there's an enemy fighter with a non-reach weapon to the bottom left (SW) of C1 or upper right (NE) of C2, which (or both) gets an AoO?

I run it the same way as Errenor.

I set the DC at the easier of the two reflex DCs.

Neither would get an AoO, just like they wouldn't get an AoO if the same diagonal were occurring without the presence of C1 and C2.

Balkoth wrote:

Errenor wrote:

I absolutely will block both diagonal movements. Provided there's no actual space in the first case and allowing (of course) tumble through in the second.

Which creature(s) is/are getting tumbled through?

Also, if there's an enemy fighter with a non-reach weapon to the bottom left (SW) of C1 or upper right (NE) of C2, which (or both) gets an AoO?

I run it the same way as Errenor.

I set the DC at the easier of the two reflex DCs.

Neither would get an AoO, just like they wouldn't get an AoO if the same diagonal were occurring without the presence of C1 and C2.

But Tumble Through very specifically states you must attempt the check "as soon as you try to enter the enemy's space" and the Success line also states "You move through the enemy's space, treating the squares in its space as difficult terrain".

Since difficult terrain only matters when entering a square, and we're moving through a space, we either trigger an AoO (because we Tumbled through, which means we entered said square and then we exited said square, fulfilling the prerequisites) or we don't need to Tumble through and we don't trigger an AoO.

As for OP's questions, with the caveat that this is how I'd run it and there really isn't anything written for pure RAWW:

1 - No, unless the PC is incorporeal/can move through walls/is mist and there's a small gap between them that the map just can't really show, etc. If it's literally two solid walls and a bog standard human PC, no.
2 - No if the wall is still solid, 90 degree wall. If the "wall" doesn't fully occupy the 5 foot space, then yes.
3 - They can move diagonally just fine.
4 - They can move diagonally just fine.

Errenor wrote:

I absolutely will block both diagonal movements. Provided there's no actual space in the first case and allowing (of course) tumble through in the second.

Which creature(s) is/are getting tumbled through?

Also, if there's an enemy fighter with a non-reach weapon to the bottom left (SW) of C1 or upper right (NE) of C2, which (or both) gets an AoO?

One creature of the player's choice.

No to moving through the wall corner.
Yes to moving between the two creatures.

I absolutely will block both diagonal movements... In the second case there's absolutely no difference between diagonal and linear, side to side arrangement of creatures in fiction...

There is absolutely a difference between diagonal and linear on PF2E battle maps. The rules for Diagonal Movement spell it out, "Because moving diagonally covers more ground, you count that movement differently." If there was no difference then there would be no difference in diagonal movement.

Extrapolating from the Diagonal Movement rules, the linear configuration is 10 feet wide while the diagonal configuration is 15 feet wide. The diagonally arranged creatures are "cover[ing] more ground."

Errenor wrote:

I absolutely will block both diagonal movements... In the second case there's absolutely no difference between diagonal and linear, side to side arrangement of creatures in fiction...

There is absolutely a difference between diagonal and linear on PF2E battle maps. The rules for Diagonal Movement spell it out, "Because moving diagonally covers more ground, you count that movement differently." If there was no difference then there would be no difference in diagonal movement.

Taken out of context. So irrelevant.

Is it really still continuous if there is 43% more open space to pass through?

The only real important part RAW is wether or not you enter the creatures space or not. Which in diagonal movement you don't, but as said when obstacles and perhaps even certain creatures fill their space all the way we are expected to adjudicate differently.

A creature doesnt give cover when its corner intersects with the line between you and your target. But a corner wall does for the same reason as above, it extends all the way and occupies the corner.

Pixel Popper wrote:

Errenor wrote:

I absolutely will block both diagonal movements... In the second case there's absolutely no difference between diagonal and linear, side to side arrangement of creatures in fiction...

There is absolutely a difference between diagonal and linear on PF2E battle maps. The rules for Diagonal Movement spell it out, "Because moving diagonally covers more ground, you count that movement differently." If there was no difference then there would be no difference in diagonal movement.

Taken out of context. So irrelevant.

Refusing to acknowledge the game rules for counting diagonals, so sophistic.

As for "more ground" - yes. Not a problem though unless somehow used as an exploit. Otherwise a 'diagonal' formation is still a continuous formation you still can't get through. Because it's 'diagonal' only on a square grid, not in fictional reality...

The square grid is what we have to work with for the battle map. You can't just handwave it away because it does fit your idea of fictional reality. And even your fictional reality is incorrect.

The linear arrangement is two dudes side-by-side spanning a 10-foot width. The diagonal arrangement is, two dudes, in a staggered formation with one 5 feet to the back and side of the other. Now, if they both turn 45 degrees to the right, without changing their center points, they are shoulder-to-shoulder spanning a distance of approximately 14.5 feet. PF2E simplifies that to 15 feet on the square battle map.

The diagonal formation may be a continuous formation, but it is more spread out, meaning there is a larger gap which the movement rules allow movement through since it can be accomplished without entering an enemy's square.

The square grid is what we have to work with for the battle map. You can't just handwave it away because it does fit your idea of fictional reality.

I absolutely can when it's justified. We also don't play chess here. And it's justified, because I don't want shenanigans with diagonal formation suddenly becoming non-formation because of 40% more space in between. It's all an abstraction and I will adjudicate it as mentioned above in this case.