Bring a tag team from Touhou 15.5 Antinomy of Common Flowers into Hollow Knight: Silksong.
What you get
Pick a duo from Reimu, Marisa, Koishi and Mokou. The picker opens the first time you play, with each character's AoCF portrait; press F8 to change your pair any time.
Your lead takes Hornet's place with her real AoCF animations, following everything Hornet does: standing, running, flying, attacking, dashing, getting hit.
Your partner floats behind you, like AoCF's master/slave system. Press E or the Taunt button (V / right stick click) to swap them.
Danmaku! Press G (or click the left stick) to fire the lead's own shot. It hits like Hornet's needle, with the same damage, and gets stronger as you upgrade the needle:
Reimu: a spread of three ofuda
Marisa: a big spinning star
Koishi: homing hearts
Mokou: a short-range fire burst that goes through enemies
Shots and swaps play each character's own AoCF sound effects, and Hornet's voice is muted.
Hornet's needle, tools, silk, healing and movement all work as normal.
You need both games. Every sprite, bullet, portrait and sound is read straight from your own installed copy of Antinomy of Common Flowers while you play. None of it is included in the download.
Single player. You can change the keys in the mod's BepInEx config file.
Credits: AoCF's file formats follow brliron's 135tk documentation (Unlicense). Hollow Knight: Silksong is by Team Cherry; Antinomy of Common Flowers is by Team Shanghai Alice and Twilight Frontier.