PoDD Info

Last updated Novemeber 07, 2018

This is a collection of information that I, Zil, have learned about Touhou 3 in my numerous years of playing it. It is still, and probably always will be, a work in progress. Bear with me as I am some kind of inarticulate autist. Here's a list of the sections with vague descriptions of what they contain. They are in no particular order.

1. Bullets, fireballs, extra attacks
Where they come from and how they behave.

2. Boss attacks, behavior, etc.
How boss attacks work, from general to specific things. Can definitely be expanded upon.

3. Triggering bosses through spell points
The ways in which spells and bosses are triggered with spell points. More or less complete with my current knowledge, not to say it can't be written better.

4. AI behavior
My understanding of the rules which govern the AI's playing. Why it gets hit, why it bombs, etc.

5. Miscellaneous
Glitches and other oddments that don't fit anywhere else.

6. Terminology
Clarification of PoDD lingo, and my inconsistent usage of it.

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1. Bullets, fireballs, extra attacks

There are two basic kinds of bullet, pellets and spell bullets. Pellets are the tiny white bullets. They are fired en masse by level 2 spells and bosses, can be created in small numbers by combos, and can be reflected by explosions. Spell bullets only come from level 3 spells and bosses. Though all characters' spell bullets look different (for instance, Marisa's are five pointed stars, Ellen's are little hearts) I am quite sure they all have the same hitbox size, and indeed are probably the same size as pellets as well.

Reflected bullets and bullets created by combos have the same behavior. First, one way or the other they will always originate from an explosion. They appear as tiny white rings and fly straight to a random spot at the top of the other player's screen. When they reach this spot they become pellets and are fired in the general direction of the other player. Reflected bullets retain their original speed while the speed of newly created bullets is determined by rank.

Extra attacks usually come from reflected fireballs, but can be created less frequently by any combo. They first appear as blue "glyphs" and fly to a point on the other player's screen where they become extra attacks. At most eight of a given player's extra attacks can exist at once, including glyphs. Some bosses can also create extra attacks directly, but these are special and do not contribute to the total.

Blue fireballs are created by combos. They explode when they touch existing explosions and can also be destroyed by direct damage, though destroying them this way doesn't make an explosion. In either case they are reflected, however. When fireballs are reflected a number of things can happen. Usually a red fireball is created, though sometimes it will be an extra attack, a red fireball and an extra attack, two red fireballs, or two extra attacks. The chance of multiple attacks seems to be much greater if the original fireball is reflected by an explosion rather than direct destruction. Red fireballs are slightly healthier than blue ones but otherwise behave identically.

Now, the aiming of fireballs is a mysterious matter. I don't understand it completely, but I'll describe what I know as best I can. Anyone who's played PoDD knows that sometimes when a wave of fireballs is launched, they all seem to aim at the player, and other times they all scatter across the screen. Which one of these things they do is actually not random. It is determined by the amount of time that has passed. Every 5 seconds, the game shifts between what I've dubbed 'scatter phase' and 'focus phase'. During scatter phase, the small red and blue orbs (soon-to-be fireballs) select a random destination at the top of the other player's screen and fly straight toward it from the place where they were created. When they reach that destination, they become fireballs and fall straight down. During focus phase, the orbs choose a destination directly above the other player's current position (that is, her position at the moment the orb was created), fly straight to it, become fireballs, and fall straight down. Every round starts out in scatter phase.
 
Of course, this is PoDD so nothing can be simple. In my testing I've found that sometimes the game is nice and changes phase every 5 seconds, with seemingly exact precision. Usually however, the timing is gradually distorted somehow. I've thought of a number of theories attempting to explain this problem. My first suspicion was that the momentary pauses from spell cut-ins would freeze the game's timer and so delay the phase shifts by about half a second for each cut-in. However, I've tested this extensively and I've concluded that this IS NOT the cause. The timer for phase shifts proceeds through spell cut-ins. In fact, even the AI's survival timer seems to keep counting seamlessly through the cut-ins.
 
My next best theory was that it is caused by slowdown. Verily, if there's any slowdown at all, it's going to distort the timer. Of course, I've been finding this problem even in matches that seem to have no slowdown at all. I eventually concluded that the game must actually be slowing very slightly: enough to gradually alter the timings over the course of a match. This explanation seemed a bit dubious to me but it was the best I could come up with. However, I've recently studied some of my older recordings from a time when I never experienced slowdown at all in this game, under any circumstances. Even in these recordings, I found that the timings deviated, seemingly at random, and so I now believe that the slowdown theory is also wrong.

Implications...

- Almost all bullets initially appear as some kind of "soon-to-be" bullet. Tiny white rings for pellets, blue glyph thingies for EX attacks, red and blue circles for fireballs. These have to physically move to the other side of the screen before they become bullets, and their movement speed is always the same. This means that when many bullets are created simultaneously, the ones that are headed toward a spot near the inner wall will arrive sooner than those headed toward the outer wall. This creates a kind of "sweeping" effect as bullets spawn across the top of the screen. (This video provides a good example: https://www.youtube.com/watch?v=xoibq3J2uFY)

- Pellets can be macro-dodged, even if hundreds of them come at you at once. Further, it's easiest to do this with counterclockwise movements. Note that if you begin on the left side of the screen, it takes the first bullets longer to reach you, and thus you are forced to move later. If you end up on the right side, the last bullets will be coming from the upper left, and so you can continue your dodge by moving upward. In the most extreme cases (for instance, when you are trapped by Chiyuri's lasers), all but the last bullets to appear can be dodged by moving straight down the left wall, and all but the first bullets can be dodged by moving straight up the right wall.

- Once fireballs are on their way, their destination is locked in. Pellets, on the other hand, aim at you when they reach the top of your screen. Knowing this, you can stand under some exploding enemies to lure the fireballs to that spot and then move the instant the opponent sends a big attack in order to misdirect the pellets.

- Because every round starts in scatter phase, and the first wave of enemies appears roughly 5 seconds into the round, casting a spell just as the first enemies appear will always result in aimed fireballs (assuming your spell is reflected) because the game will have just shifted to focus phase. This is of course only possible after having lost a round, and is a strong incentive to die with enough energy for a level 2.

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2. Boss attacks, behavior, etc.

Aside from Chiyuri's, bosses always follow the same movement path after appearing. They spawn in the upper center of the field, and start moving left at a slightly downward angle. Once they get close enough to the wall, they bounce to the right. When they get low enough on the screen they bounce upward, and so on. That takes them on exactly the same path across the field every time. Of course, some patterns cause the bosses to stop moving, but they simply start up again in whatever direction they were going. Chiyuri is different in that she teleports randomly after every pattern.

Each character's boss has a specific amount of health. The HP values for each boss are:

- 100 for Ellen and Kana
- 110 for Reimu, Mima, Marisa, Kotohime, and Rikako
- 130 for Yumemi
- 140 for Chiyuri

For an idea of what these actually mean, note that a single shot does 2 damage, and a bomb does 89/90. Credit for finding these numbers goes to Arcorann.
https://www.shrinemaiden.org/forum/index.php/topic,12670.msg896106.html#msg896106

If bosses are not destroyed they will eventually leave of their own volition by moving downward off the bottom of the screen. The amount of time they will spend on the screen before deciding to leave appears to be random. They may sometimes leave even after using just one pattern. They will always use at least one pattern though. (Note that the act of leaving the screen occurs in the place of using a pattern. i.e. they will move around a bit, or in Chiyuri's case teleport, after using their last pattern, then begin descending at the moment when they would have otherwise attacked again.) Also worth noting is that they don't actually reach the walls before changing direction, meaning that if a boss is heading straight toward you, hugging the wall will guarantee that it doesn't collide with you.

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3. Triggering bosses through spell points

Normal boss attacks can be triggered in two ways. The more straightforward method is simply casting a level 4 spell. This consumes three gauge levels and instantly triggers a boss attack, no strings attached. Note that if you try to cast a level 4 spell while your own boss is already active, you'll cast a level 3 spell instead, consuming only 2 gauge levels, as usual.

However, boss attacks can also be triggered through spell points. When your spell points reach certain values, boss attacks will be triggered automatically, at no cost. Now, the exact workings of this system are quite complex, and I may not understand them completely. I'll try to explain them as best I can, but know that there may be errors. I'll call the amount of spell points needed to trigger a boss attack at a given moment the "spell point requirement," or "SPR" for short. Initially, the SPR is 51,200. As soon as a player meets or exceeds that number, their boss attack is triggered. When that happens, the SPR is increased by 51,200, bringing it to 102,400. That means that in order for the other player to trigger a boss reversal, they'll need 102,400 spell points. Should they reach that amount, they trigger a boss reversal, and the SPR is increased by another 51,200 points, and so on. With each successive boss reversal, the SPR increases by 51,200. If at any point one of the bosses either leaves the screen on it's own or is directly destroyed, the SPR resets to its original value of 51,200.

Subtleties...

- If you destroy the opponent's boss attack or it leaves on its own while your spell points are over 51,200, you do not get an instant boss attack; however, any small increase to your spell points which occurs after the boss left but before your spell points reset will trigger a boss attack.

- Likewise, if the opponent sends a boss over, and your spell points are already above the new SPR, all you need to do to reverse the boss attack is increase your spell points by a small amount before they reset, and a reversal is triggered instantly.

- It is possible for the SPR to be raised "beyond" 655,350 (the most spell points you can have at once). In this case, the SPR actually wraps around to 10,250. Credit goes to KirbyComment for discovering this phenomenon.
https://www.twitch.tv/kirbycomment/v/91118220
https://www.shrinemaiden.org/forum/index.php/topic,8095.msg1288350.html#msg1288350

Due to the above, it can appear to those who don't know how it works that boss attacks are sometimes triggered at random; however, once you grasp the mechanics you can see that everything (usually) makes sense.

Now, about "boss panics." These are boss attacks which are accompanied by a level 3 spell (cast at the same instant as the boss attack). They are triggered at 300,000 spell points. This amount never changes. The triggering works in more or less the same ways as it does for regular boss attacks, though there are some slight differences.

- A boss panic can be triggered while you already have a boss active. This simply casts a level 3 spell.

- If you suddenly jump to 300,000 spell points, a normal boss attack is triggered, not a boss panic. If you then increase the spell points by a small amount more (and perhaps, after a certain amount of time has passed) you'll trigger the boss panic. Essentially, it seems that when you meet the requirements for a normal boss attack and a boss panic at the same time, the normal boss attack takes priority. Because of this, it's actually somewhat rare to see boss panics triggered when you didn't already have a boss onscreen.

- Once you have triggered a boss panic, you cannot trigger another one until your spell points have reset.

- Boss Panics increase the SPR just like normal boss attacks, even if you already have a boss on-screen.

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4. AI Behavior

The AI is supposed to last a certain time in each stage. The later the stage, the longer it lasts, and individual stage’s times are reduced when you lose lives to them. (i.e. dying in stage 6 shortens the time for the next round in stage 6, but stage 7 is unaffected, etc.) The way the AI actually carries this out is by taking “intentional” hits at certain times in the match. For example, in stage 1 the AI takes intentional hits at 1:00, 1:20, and 1:40 (meaning minutes:seconds elapsed since the start of the round). Also note that it's not always exact with its timing for these hits, but in general it’s pretty close.

That’s the basic idea. However, it's possible for the AI to become trapped from time to time. Usually this involves big enemies moving sideways into it, blobs of fireballs smothering it, or some characters' EX attacks exploiting its lack of foresight. When this happens, the AI bombs the instant it is hit, and this is the only situation in which the AI ever bombs. If it’s out of bombs but has a full gauge, it uses a hyper. (Note, if the AI is charging when it gets hit, it instantly releases the charge, potentially saving itself with the tenth of a second invincibility from the charge attack. I believe that if this is sufficient to avoid the hit, it doesn’t waste a bomb.) Under certain conditions, the AI stops using spells and just saves the energy for hypers. I’m not completely sure what the conditions for this are, but for starters it must at the very least be out of bombs. From there I'm not sure if simply being on the last hit point is enough, or if it must have taken more damage than expected for that point in the match, or if perhaps either of these circumstances will cause that behavior.

If the AI has no way to avoid the unintentional hit, then it just takes it, possibly causing it to die early. Furthermore, It does not make up for the unintentional hit by skipping the next intentional one, so for instance if the AI has already taken its planned first hit, and you manage to get a second hit on the AI before it takes the planned second hit, it will simply kill itself by taking a third hit when the time for what should have been the second hit arrives.

The first round (and only the first round) against Yumemi is a bit unique. She does not have any planned hits. She just survives as best she can for as long as she can. One important thing to note is that if she is reduced to her last hit point she will always start saving her spell energy for defensive hypers. As long as her gauge is full, you can be sure that she will not be killed, and that she will not use the energy to cast spells or boss attacks. Occasionally Yumemi will do this when she has more than one hit point left (see this run http://www.hitbox.tv/video/474199). This seems to be the result of her taking two hits in quick succession, so that even though she was hit twice, it will still take two more hits to kill her. In other words, her "defense mode" is activated when she has been hit twice, rather than when she's reduced to her last hit point.

A bit more about the AI's use of spell energy. I don't know what causes it to start charging up to cast a spell when the gauge is partly full, as opposed to simply saving the energy, but I do know what seem to be a few general rules about its behavior. For one, whenever its spell gauge is completely full, and its bomb stock is not empty, it will start charging up. It also tends to start charging when a round begins (i.e. when you've lost a previous round to it). Furthermore, once it has begun charging, regardless of the situation or how much energy it has, it will keep charging until the entire bar is lit up, and will then release the charge immediately. The only time it will release the charge early is when it is about to be hit while charging, in which case it releases the charge to utilize the invincibility frames, as I mentioned earlier.

Here's another thought. In PoFV at least, because of the way damage works (which I will not explain here), it is possible for the AI to take its 3 planned hits and survive due to the player having been hit just before each of the first two hits, reducing the damage taken by the AI. While damage does work similarly in PoDD, I'm not sure if it's actually possible for the AI to survive 3 planned hits, even if the player reduces the damage by taking hits just before. What little testing I've done leads me to believe that this is not possible, as the time between hits is too great. If it can happen, however, I don't know how the AI reacts afterword. It may have a backup fourth hit planned, as the PoFV AI does, or it may simply go on until it dies accidentally.

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5. Miscellaneous

This is just a list of various observations that may or may not be of any importance. This could use some organizing.

- If you trigger a boss attack, but cast a spell before it physically appears, the boss will fail to appear, though the SPR is still increased, and you will still be rewarded for the boss attack in the stage's clear bonus. If you can get your spell points up to the new SPR, you'll trigger another boss attack. If your spell points are already above that amount, (for instance if you gained over 102,400 at once, then cancelled the resulting boss attack) you just have to increase them by a small amount and you'll trigger the next boss attack. I believe it's also possible to cancel a boss attack by casting a spell immediately before the boss is triggered, though the timing window is very small. (Also note that all of this applies only to your own boss attacks. You can't cancel the opponent's boss attacks like this.) This phenomenon has some utility so I will refer to it as "boss cancelling" in the future.

- If you cast a spell while you already have a spell active on the opponent's screen, the pre-existing spell will stop as soon as the new one starts. Essentially this means you can't have two spells firing at the same time. Summoning a boss attack while you have a spell active will also cancel the spell. Kotohime's spell can only be cancelled before the mine actually spawns. Once it's appeared nothing she does will impede it, and so Kotohime alone can effectively attack with two spells at once.

- Ordinarily, spell and boss rank increase by 1 when a spell or boss is triggered, as you'd expect. However, they are also increased in some less obvious ways. When a player triggers a boss panic, that player's spell rank goes up by 3, in addition to the normal increase to boss rank. Also (and this is very strange), whenever either player destroys a boss attack by depleting its health, the next time a spell or boss is triggered (by either player) the boss rank will increase by 1, in addition to whatever would normally have been increased.

- There are 6 frames of invincibility when using a charge attack. This applies to any level of charge attack, not just level 1. You can see the character sprite's outline flash for the duration of this invincibility.

- Marisa and Chiyuri cannot shoot, bomb, or activate hypers during their charge attacks. I’ve never seen the AI shoot during a charge attack as either of those characters, though if I'm not mistaken I have seen it somehow bomb during a charge attack as Marisa.

- If you are out of bombs with a full gauge and you charge up to level 2 or 3, then activate your hyper without releasing the shot button, you cast the spell and hyper simultaneously. The normal energy cost of the spell is still subtracted from your gauge, and so the duration of the hyper is shortened by roughly 3 seconds for each section of of the gauge you lost.

- If you lose a match to Rikako while her hyper is active, the gears will still be spinning around her at the start of the next round. In this state, she can't use any charge attacks, and sometimes it seems she can't shoot either. She remains like this until she uses another hyper. Once that hyper ends, the gears will vanish and she'll be able to charge and shoot again.

- There is a limit to the number of bullets that can be on the screen at once. You see this most commonly with Yumemi and Kotohime. Strangely, I've never noticed bullets missing from a boss's attack in this game, though it happens with spells. For instance, the rings in Yumemi's spell may appear as quarter circles rather than complete rings if fired at the same time as her boss's cloud of death. Kotohime's mines can be missing some or all of their bullets if two of them explode at the same time.

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6. Terminology

For the sake of everyone's sanity, let me define some things that may be unclear.

Boss attack / pattern = I use "boss attack" inconsistently to refer to bosses themselves (which agrees with the game's usage) and the bullet patterns they create. I'll try to avoid this and say "pattern" or something, but I might do it without realizing.

Chain / combo = Other words I use inconsistently, so let's try to set it in stone. I would say that a "combo" is everything that results from your destruction of a single enemy such that the hit counter is increased without resetting. I think that's sensible since your highest value for the hit counter is called "MAX combo" in the clear bonus. A "chain" then is a series of combos that are strung together such that the spell points are increased without resetting.

Enemy = I'm terrible about this. Generally when I say "enemy" I mean the little ghosts/stars/moons/etc. I try to call the other character (the one you're fighting) the "opponent" or something. I think, ideally, we'd call the ghosts and stars "zako" like people do in Twinkle Star Sprites and other games, but this will require lots of rewriting, and I'm lazy... so lazy...

Hyper = When you have no bombs, your gauge is full, and you press the bomb button. The appropriate term for this, if I'm not mistaken, is "charge max ability", but people have been calling it hyper since ancient times.

Level 2, etc. = "Level 2" is just short for "level 2 spell". Also sometimes shortened further to "lvl2" or somesuch.