Games like Kill the Demon Lord
Games like Kill the Demon Lord include TEVI, Rabi-Ribi, Touhou Hero of Ice Fairy, Black Myth: Wukong, and Last Command. We matched them by the tags players give Kill the Demon Lord on Steam (Bullet Hell, Action, Top-Down Shooter, Visual Novel, and Action-Adventure): closest matches first, and among equally close ones the better-known games.

TEVI
Shared: Bullet Hell · Action-Adventure · Anime

Rabi-Ribi
Shared: Bullet Hell · Female Protagonist · Anime

Touhou Hero of Ice Fairy
Shared: Bullet Hell · Female Protagonist · Anime

Black Myth: Wukong
Shared: Action · Action-Adventure · Story Rich

Last Command
Shared: Bullet Hell · Action · 2D

Tomb Raider Game of the Year
Shared: Action · Female Protagonist · Story Rich

Rise of the Tomb Raider™
Shared: Action · Female Protagonist · Action-Adventure

Wuthering Waves
Shared: Action · Anime · Story Rich

ICEY
Shared: Action · Female Protagonist · Anime

OPUS: Echo of Starsong - Full Bloom Edition
Shared: Visual Novel · Female Protagonist · Story Rich

BlazBlue Entropy Effect
Shared: Action · Action-Adventure · 2D

SANABI
Shared: Action · Story Rich · 2D

Danganronpa Another Episode: Ultra Despair Girls
Shared: Action · Female Protagonist · Anime

Vampire Survivors
Shared: Bullet Hell · 2D · Action

WITCH ON THE HOLY NIGHT
Shared: Visual Novel · Anime · 2D

永远消失的幻想乡 ~ The Disappearing of Gensokyo
Shared: Bullet Hell · Action · Female Protagonist

AI LIMIT
Shared: Female Protagonist · Action · Anime

BALL x PIT
Shared: Action · Bullet Hell · Top-Down Shooter

Touhou: Scarlet Curiosity
Shared: Bullet Hell · Action · Female Protagonist

Touhou Koumakyou: New Classic - the Embodiment of Scarlet Devil
Shared: Bullet Hell · Action · Female Protagonist

Stellar Blade™
Shared: Action · Female Protagonist · Action-Adventure

fault - milestone two side:above
Shared: Visual Novel · Female Protagonist · Story Rich

Touhou Juuouen 〜 Unfinished Dream of All Living Ghost.
Shared: Action · Bullet Hell · Female Protagonist

The Vagrant
Shared: Action · Female Protagonist · 2D