It's the middle of summer... or at least it should be. The Hakurei Shrine is experiencing spring, the Forest of Magic is in the depths of winter, while Youkai Mountain is covered in the golden leaves of autumn. Reimu Hakurei, Marisa Kirisame, Aya Shameimaru and Cirno (with a tan!) set out to investigate.
The game features the Sub-Season system - in addition to selecting from one of four Player Characters (each with a different seasonal theme), the player also selects one season as a subweapon. Subweapons add additional bullets to the player's shot, have a separate power meter charged by collecting season items, and allow the player to expend some of their seasonal power to perform a "mini-bomb" called a Season Release (which converts nearby bullets into point items).
Notably, this game was the first one made commercially available outside of Japan. You can get it on Steam here.
This game provides examples of:
- 11th-Hour Superpower: Due to being guaranteed to lose against Okina if they use the normal sub-seasons, the heroines instead use a special "Fifth Season" option exclusive to the Extra Stage, which is tailor-made for the stage structure.
- Achievements in Ignorance: Unlike the other characters, Cirno doesn't realise that she's drawing power from an external source - she just thinks she's developed a cool suntan. Cirno using the power of the Fifth Season in the Extra Stage also seems to be nothing more than a freak coincidence, though Okina takes it as evidence that Eternity Larva (whose door Cirno used to reach the Extra Stage) might be much more than she seems.
- The Battle Didn't Count: The heroines actually fail to defeat the Final Boss in the good endings, as her final attack is taking away your options and all your Power, and using it to throw a sadistic multi-stage attack your way, which led to them retreating. However, they swear to avenge themselves, and do so by rematching Okina in the Extra Stage.
- Bizarre Seasons: The incident is that all four seasons are occurring at once in different parts of Gensokyo.
- Dual Boss: Mai Teireida and Satono Nishida first appear as the midbosses for Stages 4 and 5, respectively, before coming together to serve as the Stage 5 bosses. Yes, the gimmick of the Stage 5 boss this time is being a Dual Boss. They later reappear as the midbosses of the Extra Stage.
- Element No. 5: Or rather, Season Number Five. While the main game offers the standard four seasons, in the extra stage the heroines use the power of "The Fifth Season", that is, doyou, the intermediary periods between seasons where lifeforce is at its weakest and is associated with The Power of the Void.
- Idiosyncratic Difficulty Levels: Following the game's theme, the difficulty levels are named after seasons and weathers.
- Easy: Spring Sprinkle
- Normal: Summer Shower
- Hard: Autumn Typhoon
- Lunatic: Winter Hibernation
- Extra: The Fifth Season
- In the Back: This game eventually reveals itself to have a fascination with "back doors", which is exemplified when the Final Boss and her flunkies are fond of shooting you from behind with several of their spellcards. Taken to its logical extreme in the Extra Stage, where not only are there several waves of enemies shooting you from behind, entire spellcards are made completely around the idea of shooting you from behind or having Mooks do it. In any other game a stage made wholly around this idea would be nightmarish to deal with, even for Extra Stage standards, so to balance it out your heroines have a fixed, powerful Extra Stage-exclusive option that shoots directly behind you, and which can be used to form up small, temporary barriers behind you. So yes, prepare to spend at least half your time playing from the top of the stage and intercepting downwards.
- It's Personal: Even if the heroines don't do anything, the incident will eventually resolve itself—but the humiliation the Final Boss visited on the heroines will not be forgiven, and so the Extra Stage of the game is the second invasion of Ushirodo-no-Kuni, with the intention of challenging Okina to a rematch and kicking her ass. To drive the point further, the Extra Difficulty description declares this to be the heroines' counterattack (instead of the usual warning to not try this thing out), and the stage header that traditionally reads "Extra Stage" instead says Revenging Stage.
- Multi-Stage Battle: The first four levels each corresponds to a season, the Gensokyo Sky (Summer), Youkai Mountain (Autumn), Hakurei Shrine (Spring), and Forest of Magic (Winter). During the final battle with Okina, she teleports you to one of these locations after each spellcard, which also correspond to what seasonal power she'll attack you next with.
- Portal Crossroad World: We're introduced to the Ushirodo-no-Kuni (The Land of the Rear Door), filled with many doors that go to every possible place in Gensokyo, it's the setting for the latter half of the game.
- Remember the New Girl?: The first four stages are each associated with a different protagonist, introducing a new character who has some kind of pre-existing connection to them:
- Eternity Larva is a fairy themed not after an insubstantial force but a swallowtail butterfly, with a Non-Standard Character Design to go with it. Despite being unprecedented for the player, however, this isn't considered unusual by other fairies like Cirno.
- Nemuno Sakata's people live on Youkai Mountain, with a pact that forbids tengu like Aya from trespassing freely.
- Aunn Komano claims she's always been around the shrine, cheering Reimu on, though none of the cast seem sure who she is because, as revealed in Wild and Horned Hermit, she was created only recently when Okina imbued her power into a statue.
- Narumi Yatadera is one of Marisa's neighbours in the Forest of Magic, as well as a fellow magician, though Marisa describes her as a "shut-in introvert".
- Seasonal Motif: Each of the first four stages corresponds to a different season and Player Character, with that character drawing upon the season's power - Spring (Reimu), Summer (Cirno), Autumn (Aya) and Winter (Marisa).
- Strong as They Need to Be: Canonically, the heroines are unable to overcome Okina's final spellcard and retreat, since they were attempting to defeat Okina with powers granted by Okina, only to have the tables turned on them. It's not until they harness the "fifth season" that they actually are able to defeat Okina, and even then, for Cirno, it's theorized that she received help from another god who is enemies with Okina.