Touhou Eiyashou ~ Imperishable Night (東方永夜抄 〜 Imperishable Night lit. Eternal Night Vignette from the East) is the eighth official game of the Touhou Project scrolling shooter series by Team Shanghai Alice. It is the third Touhou game to be released specifically for the Windows operating system. It was first released in the 66th Comiket on August 15, 2004.
Gameplay
Imperishable Night plays like a fairly typical vertically scrolling danmaku shooting game, 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.
Quite a few details are unique to this game, including Last Spells — for an enemy, a Last Spell is a bonus Spell Card which the player can tackle with the challenge to not to die. On the player side, Last Spells are secondary "bomb" Spell Cards, which last longer/do much more damage at the expense of two bomb stocks. There is a gauge which tracks how human/youkai (normal/focused) the player is, as well as a new "Time" system, which affects gameplay.
Time
Every stage has a time counter, which, despite what the name might imply, requires the player to collect a certain amount of "time points". If the player fails to collect the required amount by the end of the stage, the clock, which tracks the frozen time in Gensokyo, shifts one hour ahead. Otherwise, the clock only advances half an hour. The clock starts at PM 11:00; if the player ever reaches AM 5:00 in-game, the player is given a bad ending. Having to continue also advances the clock by half an hour.
Time points are collected via shooting down when playing as a human, or from grazing bullets when playing as yōkai. If the player loses a life, some time points are deducted. Also, when playing on difficulties Normal or higher, filling the time counter for a stage also unlocks the Last Spell for that stage's boss.
Human-yōkai pairs
Imperishable Night features a total of eight playable characters, in pre-set pairs (and later, individually). The pairs, one human and one yōkai, work in tandem: one person fires when unfocused, while the other pops in and fires when focused, with a reduction in movement speed. The two attacks can be drastically different. The individual characters do not have an attack change when focused, although the movement of player familiars (such as Remilia's) may change.
A gauge on the lower left corner of the screen keeps track of how human or yōkai the player is, and affects the player's score accordingly. The gauge, ranging from -100% (human) to 100% (yōkai), is determined by which mode the player uses more. When the player reaches ±80%, they can collect time orbs by hitting enemies (as a human) or by grazing against bosses and killing enemies (as a yōkai). Since it is important to collect as many time orbs as possible (to slow time and get high scores), the player should try to keep the gauge either below -80% or above 80%. Because Youmu Konpaku of the Netherworld Dwellers team is half-ghost, their gauges are adjusted accordingly (-50% to 50% solo, -50% to 100% as the team), and the minimum values for time orb collection are reduced. Youmu is the only character that can collect time orbs in both ways because of this.
Some enemies use familiars that change their vulnerabilities accordingly depending on whether the player is playing as a human or a yōkai at the moment. These familiars are completely invulnerable when the player switched to a yōkai, but at the same time these familiars cannot collide with the yōkai player and do not shoot bullets when the player is on top of them. The enemies' alternating vulnerabilities in this game draw comparisons with Ikaruga. Bosses may also change their standard attacks depending on the orientation of the player, usually firing slower bullets and/or homing bullets when the player is a yōkai.
Spell Practice Mode
The Spell Practice Mode is unlocked by beating the game with the normal ending (i.e. before the game time reaches 5:00 am). This feature allows a character/team to practice a spell card (bullet pattern) they have already seen in the Story Mode and Extra Mode. In this mode, players have only one life and cannot bomb, and is only able to clear a spell card by shooting down the boss before time runs out without being hit. Clearing spell cards here will show the creator's own comments on the spell cards or the characters associated with them.
Only available in the Spell Practice Mode are Last Words, which are typically the hardest spell cards in the game. These spells are earned by accomplishing certain feats such as beating the game using certain characters/difficulties or seeing/mastering a sufficient number of spell cards.
Plot
It is the eve of the Harvest Moon Festival in Gensokyo when the youkai sense that something is wrong with the moon. It appears that the moon has been replaced by a fake moon that can never become full. In order to find the real moon before sunrise, the protagonists extended the night to make an imperishable night, and set out to find the culprit.
After minor skirmishes along the way, including a battle with a fellow culprit-seeker, the protagonists reaches Eientei, the mansion of the perpetrator. Once inside, they find that the mansion is guarded by the moon rabbit Reisen Udongein Inaba, whose ability can cause disorientation. From here, the team may either choose the path that leads to the fake moon conjured by Eirin Yagokoro, or the real moon, where the moon princess Kaguya Houraisan is hiding. It is then realized that the moon was swapped in order to sever the link between the earth and the moon to hide Kaguya from the lunar emissaries who seek to bring her back. The team then accepts Kaguya's "Five Impossible Requests" and fight until daybreak.
Having completed the Five Impossible Requests, the team is given another challenge by Kaguya in the Extra Mode: defeat her rival, Fujiwara no Mokou.
