The basic story premise of PatchCon! has Patchouli Knowledge being unable to bear any more library raids by Marisa, she needed somebody strong to help defend it instead of the Scarlet Devil Mansion's pathetic maids. Patchouli used a spell to manufacture dolls infused with the hair of certain proprietors that would help protect her library by taking their forms and abilities. However, someone stolen the doll manufacturing process and began making rival dolls to ransack the library of it's books.
At the start of each game, you select a team of five Touhou characters, each with their unique attacks, strengths and weaknesses. The game starts the player off with the Scarlet Devil Mansion residence (Patchouli Knowledge, Remilia and Flandre Scarlet, Sakuya Izayoi, and Hong Meiling), though the number of teams increases as players completes the game multiple times. The objective is to make sure all Patchouli's books doesn't get attacked by the enemies until the clock strikes midnight, but if all 20 books are destroyed, it's Game Over.
A fan-translation patch can be found here.
This game provides examples of:
- Asteroids Monster: The Suika unit splits into two Mini Suika units upon defeat. Mini Suika units split into two Teeny Suika units upon defeat.
- Elemental Powers: Your five spell cards are based on the Eastern elements of Fire, Water, Earth, Wood, and Metal.
- Endless Game: The Endless Mode.
- Excuse Plot
- Giant Mook: Every few game hours or so, a pair of giant versions of one of the characters will appear. They take lots more punishment than the regular-sized enemies. In Boss Rush mode, all enemies are giants.
- Hold the Line: Defend the library (from evil dolls that wants Patchouli's books)!
- Spectacular Spinning: The Hina units.
- Spread Shot: A common upgrade for the Danmaku types.
- Tactical Rock–Paper–Scissors: There are three types of characters: Melee, Danmaku, and Flying. The Melee units take enough punishment to close with Danmaku units, which have long range attacks and tend to take Flying units down quickly, which are also slow but powerful ranged units that tend to hit in a large area and take down Melee units in a couple hits.
- Taking You with Me: Meiling and Mokou are both Melee units that explode when destroyed.
- Tower Defense: There is a mode like this
- Zerg Rush: Averted. Yes, it is tempting to fill over half the screen with hundreds of Level 1 Cirnos (the cheapest Melee unit) in 100k Modenote , but a mob of level 4 Reimus (Flying) will make shaved ice out of them.
- Also, Alice spawns at Level 1 with two Melee dolls, and gains an additional doll every few levels thereafter. Twenty of those, pumped up by a few levels, gives you eighty respawning melee units as well as twenty fairly powerful gunners.
- You can force this upon yourself by rapidly clicking the button to spawn the next wave of enemies, eventually spawning all of the enemies that would have been spawned over the course of the game all at once.