Games like Prologue for a Vacant Kingdom
Games like Prologue for a Vacant Kingdom include Relic Hunters Zero: Remix, Enter the Gungeon, Dungeon Munchies, 20 Minutes Till Dawn, and Touhou Blooming Chaos 2. We matched them by the tags players give Prologue for a Vacant Kingdom on Steam (Bullet Hell, Free to Play, Action, RPG, and Indie): closest matches first, and among equally close ones the better-known games.

Relic Hunters Zero: Remix
Shared: Action · Free to Play · Twin Stick Shooter

Enter the Gungeon
Shared: Bullet Hell · Indie · Difficult

Dungeon Munchies
Shared: Action · Indie · RPG

20 Minutes Till Dawn
Shared: Bullet Hell · Shoot 'Em Up · Top-Down Shooter

Touhou Blooming Chaos 2
Shared: Action · Bullet Hell · RPG

Nuclear Throne
Shared: Bullet Hell · Indie · Action

Bloody Hell
Shared: Bullet Hell · Indie · Free to Play

Warframe
Shared: Free to Play · Action · RPG

Voidigo
Shared: Bullet Hell · Twin Stick Shooter · Shoot 'Em Up

The Ascent
Shared: RPG · Action · Top-Down Shooter

Cyberhunt
Shared: Action · Indie · Shoot 'Em Up

Vampire Survivors
Shared: Bullet Hell · Indie · Action

Neverwinter
Shared: Free to Play · RPG · Action

Wuthering Waves
Shared: Free to Play · Action · RPG

BALL x PIT
Shared: Action · Bullet Hell · Shoot 'Em Up

Exit the Gungeon
Shared: Action · Bullet Hell · Indie

Hyper Light Drifter
Shared: Indie · Action · Adventure

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

Bot Vice
Shared: Bullet Hell · Shoot 'Em Up · Top-Down Shooter

Marvel Rivals
Shared: Free to Play · Action · RPG

SMITE®
Shared: Free to Play · Action · Indie

DELTARUNE
Shared: Bullet Hell · RPG · Funny

Once Human
Shared: Free to Play · Action · RPG

Star of Providence
Shared: Bullet Hell · Indie · Shoot 'Em Up