The Shrine Maiden series, or "Toho series", consists of a number of mostly shooting games for PC – the first five to the japanese OS PC98, and the sixth and onwards for Windows 95 and up.
Created by pseudonym ZUN (Junya Oota), the Toho series has become famous for its hysterical and colourful "curtain fire" mass-bullet dodging and invigourating music. The story is set in an area called the "Land of illusionary thoughts", or "Gensokyo", placed on the border between the human world and the spirit world. Here lives the shrine maiden (miko) Reimu Hakurei, in the Hakurei shrine. As it's lying on the border of the spirit world, monsters, spirits, ghosts, and various occult creatures frequently leak out into Gensokyou. Reimu's a laid-back, each-day-as-it-comes young woman, and the usual motives for departing to defeat evil is so that she can have her cup of tea in peace.
As the games have developed, the character gallery (consisting of only girls) has grown explosively. All stage bosses in the games are named characters, and there is always some dialogue going on, which means that each game effectively introduces something around six new characters. Some characters have become more famous than others, some return as playable characters in later games. The by far most recurring character is the human witch Marisa Kirisame, another recurring character is the doll-user Alice Margatroid, the knife-wielding maid Sakuya Izayoi, and many more. With ZUN's "free for all" attitude towards his own franchise, fanzines, spin-off games and flash animations have exploded on the market, making the fandom around the Shrine Maiden series much larger than for any commercial game. At the Japanese bi-annual fanzine market Comics Market, the amount of fan-made material for the Shrine Maiden franchise is bigger than for all other video games combined.
As with all shooting games, delving deeper, the games are about trying to beat a high-score, and the Shrine Maiden series have had the same basic principle for this during all games: Some enemies, when shot down, drop point items, and the higher up on the screen the player collects these point items, the higher the points they gain. What separates the games from each other is (mostly) how to increase the maximum amount of points a point item can yield. In Lotus Land Story there were the Dream items that, when collected, would increase each point item's worth. In Mystic Square, collecting Dream gradually lowered the "max point line", the horisontal line above which the point items would give maximum points. In Scarlet Devil, the now-characteristic of the Shrine Maiden games was introduced; flying at the top quarter of the screen would cause the player to automatically absorb all items on screen, something that has followed in all subsequent games. In Cherry Blossom, the system to increase the max point for the point items was a combination of scraping the bullet streams, not bombing and absolutely never dying. In Imperishable Night, the max point for the point items slowly increased as long as you stayed in human form or ghost form. In Mountain of Faith, it was a matter of upholding a chain of killed enemies, and in Subterranean Animism, continuously scraping bullet streams could be a substitute for flying on the top quarter.
The Shrine Maiden series consist of:
東方靈異伝 〜 Highly Responsive to Prayers "Toho Reiiden" (PC98, 1996) – arkanoid-type game.
東方封魔録 〜 the Story of Eastern Wonderland "Toho Fujinroku" (PC98, 1997) – shooting
東方夢時空 〜 Phantasmagoria of Dimension Dream "Toho Mujiku" (PC98, 1997) – VS shooting
東方幻想郷 〜 Lotus Land Story "Toho Gensokyo" (PC98, 1998) – shooting
東方怪綺談 〜 Mystic Square "Toho Kaikidan" (PC98, 1998) – shooting
東方紅魔郷 〜 The Embodiment of Scarlet Devil "Toho Komakyo" (Windows, 2002) – shooting
東方妖々夢 〜 Perfect Cherry Blossom "Toho Yoyomu" (Windows, 2003) – shooting
東方永夜抄 〜 Imperishable Night "Toho Eiyasho" (Windows, 2004) – shooting
東方花映塚 〜 Phantasmagoria of Flower View "Toho Kaeizuka" (Windows, 2005) – VS shooting
東方文花帖 〜 Shoot the Bullet "Toho Bunkacho" (Windows, 2005) – bullet hell screenshot taking game
東方風神録 〜 Mountain of Faith "Toho Fujinroku" (Windows, 2007) – shooting
東方地霊殿 〜 Subterranean Animism "Toho Chireiden" (Windows, 2008) – shooting
東方星蓮船 〜 Undefined Fantastic Object "Toho Seirensen" (Windows, 2009) – shooting
ダブルスポイラー 〜 東方文花帖 "Double Spoiler – Toho Bunkacho" (Windows, 2010) – bullet hell screenshot taking game
妖精大戦争 ～ 東方三月精 "Yousei Daisensou - Toho Sangetsusei" (Windows, 2010) - bullet hell freezing game
東方神霊廟 ～ Ten Desires "Toho Shinreibyou" (Windows, 2011) – shooting
and the three fightergame spinoffs, made by the game circle Twilight Frontier:
東方萃夢想 〜 Immaterial and Missing Power "Toho Suimuso" (Windows, 2004)
東方緋想天 〜 Scarlet Weather Rhapsody "Toho Hisoten" (Windows, 2008)
東方非想天則 〜 超弩級ギニョルの謎を追え "Toho Hisotensoku" (Windows, 2009) (a standalone expansion to Scarlet Weather Rhapsody)