Book of Star Mythology/Gameplay

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Title screen of the game

This article describes the overall gameplay and background information for Book of Star Mythology.



The game may be played using either a keyboard or a gamepad. Keyboard controls are as follows:

  • The Arrow Keys move the character around
  • Z causes a short barrage of shots to be fired; it may be held down for rapid fire
  • X releases a bomb, also known as a spell card or spiritual attack (presuming you have bombs left)
  •  Shift slows the character's movement, and changes the nature of the character's shot; it generally makes your attacks more focused.
  • Esc pauses the game and brings you to the in-game menu
  • Q returns you to the title screen when the game is paused
  • R returns you to the beginning of stage 1 when the game is paused
  •  Shift+C in the pause screen returns you to the title screen.
  • Ctrl fast-forwards through any dialogue and replays
  • Home or P produces a .bmp screenshot in the /snapshot directory.
  • Alt+Enter switches the game to full screen mode
  • Left Ctrl speeds up the game

Basic Gameplay

Book of Star Mythology plays like a fairly typical vertically-scrolling danmaku shooting game like any Touhou Project fangame would, in which the player's character is always facing towards the top of the screen, shooting at anything that moves, avoiding and weaving between enemy bullets, and confronting difficult bosses at the end of a stage.

The game includes a mode called "Legendary Hero Mode", which is like Legacy of Lunatic Kingdom's Pointdevice mode, except this new mode gives the player infinite lives. Ranks are given out depending on your score and how many times you get hit. Legacy mode plays out like a typical Touhou Project game (you can earn ranks here as well).

There are 4 levels of difficulty: Easy, Normal, Hard, and Lunatic. Each difficulty level features differences in the number of bullets fired by each enemy, rate of fire, variations in the bullets' pattern of movement, and the number and type of enemy spell cards used. Also, power items will not be in this game. Instead, you remain at full power the whole time.


A character's "shot" is the player's primary method of attacking enemies. The shot's attack area and behavior varies depending on the character and attack type the player has chosen, as well as whether the player is focused or unfocused. At a close range, the player's shots do more damage.

Point of Collection

Like many Touhou games, there's a line most of the way up the screen called the point of collection. If you move your character at or above this line, all items on the screen will be drawn to your character. Like the official Touhou games from Mountain of Faith onward, you don't need to have full power or focus to use the POC – it's always available. If you were to continuously shoot down enemies, the POC (represented by a blue arrow on the left side of the screen) will be lowered temporarily.


Like the official games, Book of Star Mythology features bombs (actually spell cards) with distinctive visual styles that differ between characters. A character's "bomb" is the player's limited-use method of getting out of difficult situations. A bomb's attack area, duration, and power varies depending on the character the player has chosen, but it typically deals heavy damage to every enemy it touches, in addition to canceling out any bullets in the bomb's way, as well as automatically collecting every item on screen.

At the beginning of the game, you will start off with 3 bombs. Extra bombs are obtained by collecting 3 bomb pieces. Bomb pieces are collected by doing chapters without dying, as well as getting 333 wish items in legendary hero mode.

You can carry up to a maximum of 8 bombs at a time. If you collect a bomb piece when you already have 8 bombs, that bomb piece will be lost. Like in the earlier Touhou games, after dying the number of bombs will reset to the initial value of 3 bombs. Accumulated bomb pieces are preserved when the player loses a life. The counter is reset to 0 upon continuing after a game over, however.

As usual, deathbombing is a game mechanic. After being hit by a bullet, the player is given a brief window of time to bomb and negate their death. The "death" sound effect will play, and the bomb will then activate. You cannot deathbomb on Legendary Hero Mode, due to it being unneeded due to infinite lives.


The hit box for your character is quite small in comparison to your on-screen sprite, approximately only 5×5 in pixel size. If you hold Shift, a colored dot will appear, showing the hitbox precisely. If the hit box of a character comes into contact with the hit box of an enemy bullet, laser, or the enemy itself, then you have been hit.

In Legendary Hero Mode, lives are not used. Instead, you are given infinite lives.

In Legacy Mode, you start off the game with 3 lives (that is, 2 extra lives). You can lose a life by getting "hit" by an enemy attack.

In this game, the player's life stock is represented by a health bar with hearts. Extra lives are obtained by collecting three life pieces, you get one piece per 333 wish items for one life every 999 wish items.

You can carry up to a maximum of 8 extra lives at a time. If you receive an extra life when you already have the maximum, that life will be lost.

When you lose a life, all the bullets on the screen are cleared, and you become invulnerable for a short period of time.

Upon losing all their lives, the player is given the choice to continue right where they left off. However, if you do continue, your current score will be reset back to 0, plus the number of times you have continued. The number of bombs will be reset to its default of 3, and you can no longer save a replay after continuing.


Each stage is subdivided into chapters. The boundaries between chapters, or way points, correspond to fixed points within the stage, as well as after every boss attack. When the player passes a chapter they will receive a Chapter Finish Bonus (below). In addition, in Legendary Hero Mode, you are given the option of reviving on the spot you died or at the bottom of the screen, unlike Pointdevice Mode. When you complete a chapter without dying, you receive a bomb piece.

Wish Items

The game introduces wish items, which are transparent star-shaped pieces that enemies drop whenever they're defeated. The wish items increase the maximum value of point items. They are dropped from enemies, and they also 'bleed' them when you are close to them, including bosses - the closer you are to them, the more health they have and the faster you deplete their health relative to how much they have, the more wish items you gain from being close to enemies in a given time frame. The amount of point item value increased per wish item scales with difficulty as such:

Difficulty Easy Normal Hard Lunatic Extra
PIV per wish item 8 10 15 20 30

If you collect 333 wish items, you can earn a spell fragment in Legendary Hero Mode and a life fragment in Legacy Mode. This number is decreased to 100 wish items in extra.

Boss Battles

The main challenge and the main attraction that appears at the end of each stage. Each boss has multiple lives, which are represented by stars shown at the upper left of the screen. Bosses usually alternate between attacking normally and attacking with spell cards, switching once with each health bar. Markers on the health bar indicate the start of a spell card attack when the boss' health is depleted that far.

Normal attacks are typically incrementally stronger versions of the boss character's basic attack. Spell card attacks bedazzle the player with combinations of complex patterns that often involve the use of projectiles and obstacles crafted especially for use with that spell card. If the player manages to defeat a spell card attack without getting hit or using any bombs, a substantial score bonus is rewarded for the feat.

Each attack is accompanied by a timer. When time runs out, the boss will switch to their next attack pattern even if their health bar isn't empty. Waiting for a boss's attack pattern to self-destruct may be enough to beat them, but mere survival won't earn the player any score bonuses. The exception however is when the boss is invulnerable for the duration of the spell card; in this case the player will receive the bonus on survival.

When fighting a boss, a position marker shows up on the bottom margin of the screen, indicating where the boss is on the horizontal axis. Since your target can be completely obscured by bullets or darkness at times, use this marker to help you aim your shots. The marker will dim when the boss is being hit, and will flash red when her health bar gets sufficiently depleted.


There are three characters to choose from in the game, each with two shot types. Most of the types are similar to recent games such as Ten Desires and Double Dealing Character. Strangely, each character will use the same spell card for both shot types.

Constellation Gauge and Magnitude

The April 2nd trial introduced the Constellation Gauge and its Magnitude mechanic. The Constellation Gauge gradually fills up as you collect wish items. When the gauge is full, the Magnitude increases and either a life or spell piece is produced. The lowest Magnitude is 6, while the highest is 1. Increasing your Magnitude makes the multiplier next to it go up by 0.6. Magnitude will go down by one level if you die. The multiplier for each Magnitude level is:

Magnitude 6 5 4 3 2 1
Multiplier 1.0x 1.6x 2.2x 2.8x 3.4x 4.0x

Multiplier will continue to increase even after you've reached your maximum Magnitude, by 0.05 per level instead of 0.6. Capturing spell cards will also increase it by one level.

There's also a number to the left of the Constellation Gauge, which is also decreased by wish items and which resets at the beginning of each stage. Once it's depleted, you will take on the powerful Lastword spell card from that stage's boss. Failing these will not take away resources and won't count as dying (so you will still get a bomb piece), but the spellcard automatically ends without the spell dying, losing both the spell card and chapter bonus, as well as the wish items dropped at the end if you capture the spell.



Any damage you deal to any stage enemy, whether it'd be caused by your shots or your bombs, will cause your score to increase slightly. Destroying enemies will award slightly more. Unlike other games, the gain from this is slightly relevant in terms of score gain because it scales with point item value and multiplier. More importantly, destroyed enemies release items for you to collect, and those are very important for scoring as covered below.


"Grazing" is the act of having a bullet pass near one's hitbox. Point Item Value will increase by 10 for every 5 graze.

Point Items

As its name implies, point items are a major source of points in the game. The higher up on the screen you collect them, the more points they're worth, up to a defined maximum. You can easily tell when you are collecting point items for their maximum value, since they'll show the value in yellow text. The auto-item-collect line is the same height as the height where point items reach their maximum value, so take advantage of this fact whenever you can for massive points. As in Undefined Fantastic Object onward, auto-collected items are still worth their full value if you happen to leave the auto-collect area before items contact your hit box, or if they're auto-collected in another manner such as by bombing or dialogue.

The point items' starting value varies by difficulty:

Difficulty Easy Normal Hard Lunatic Extra
Starting value 10,000 15,000 20,000 25,000 30,000

The point item value is increased by grazing, collecting wish items, and collecting green point value items. These items are released by cancelling enemy bullets, which can come from finishing a boss spell card, or using a bomb. However, spell cards won't produce green items when timed out, and non spells do not produce green items from being finished off. The score gain for collecting green point items increases with point item value and multiplier. Point Item Value also increases the point gain for shooting enemies and cancelling bullets.

Point Item Value will increase up until 999,990. This is the same on every difficulty.

Spell Card Bonus

Occasionally, a boss will attack using a spell card. You'll know this is happening when the background changes and the spell card's name appears in the upper right corner of the screen. If the boss's health bar is depleted within the time limit and without getting hit or using a bomb, the spell card bonus will be added to your score. Whenever you capture a spell card, your magnitude will be increased by one level.

The starting value is a simple function of difficulty, point item value and multiplier:

Base Value * Point Item Value * Multiplier

Where the base value is a multiplier dependent on difficulty:

Difficulty Easy Normal Hard Lunatic Extra
Base Value 66 86 102 120 240

Collecting wish items during a spell card will increase the value of capturing it, which is scaled in the same way.

Chapter Finish Bonus

The Chapter Finish bonus is awarded whenever the player passes a waypoint. The amount of wish items collected and the proportion of enemies defeated in the chapter are totaled, and the bonus is then calculated as follows:

Wish Items × Shooting Down % × Point Item Value × Multiplier / (1 + Number of Deaths)

If the player does not die, the player will be awarded a bomb fragment in Legendary Hero Mode, or a life fragment in Legacy Mode.

Clear Bonus

At the end of a stage, the player is awarded a clear bonus. The clear bonuses increase based on difficulty and stage number, but in the main game does not vary based on resources.

Extra's clear bonus scales based on the amount of resources left and is much larger.


At the end of a run, you are given a rank. This rank is calculated as shown:

Score / 100,000,000 - (DEATH_RATE * n) 

Where N is a multiplier based on difficulty.

Difficulty Easy Normal Hard Lunatic
Starting value 0.75 1 1.5 2

DEATH_RATE is calculated as follows on Legacy mode: (Number of Deaths - 5) * 2. On Legendary Hero mode, it is set to your number of deaths.

For example, with 20 billion on lunatic with no deaths, this would result in a rank value of 220.

Your rank is then calculated depending on the difficulty. There are 8 ranks. To get a rank, get a score higher than the score listed for the rank in a specific difficulty as listed in these tables.


Rank Mizar Hamal Deneb Spica Altair Vega Canopus Sirius Sun
Starting value 0 < 10 10 20 30 40 60 80 110


Rank Mizar Hamal Deneb Spica Altair Vega Canopus Sirius Sun
Starting value 0 < 14 14 28 40 53 77 105 140


Rank Mizar Hamal Deneb Spica Altair Vega Canopus Sirius Sun
Starting value 0 < 18 18 35 55 75 105 150 200


Rank Mizar Hamal Deneb Spica Altair Vega Canopus Sirius Sun
Starting value 0 < 20 20 45 67 90 130 175 240