Games like Hell Slayer
Games like Hell Slayer include Halls of Torment, Death Must Die, Vampire Survivors, Hero Siege, and Soulstone Survivors. We matched them by the tags players give Hell Slayer on Steam (Action, RPG, Action Roguelike, Action RPG, and Bullet Hell): closest matches first, and among equally close ones the better-known games.

Halls of Torment
Shared: Action Roguelike · Bullet Hell · Roguelite

Death Must Die
Shared: Action Roguelike · RPG · Bullet Hell

Vampire Survivors
Shared: Action Roguelike · Bullet Hell · Roguelite

Hero Siege
Shared: Action RPG · Action Roguelike · RPG

Soulstone Survivors
Shared: Action Roguelike · Action RPG · Bullet Hell

BALL x PIT
Shared: Action · Roguelite · Bullet Hell

Black Myth: Wukong
Shared: Action · Action RPG · RPG

Hades II
Shared: Action · Action Roguelike · Roguelite

Heroes of Hammerwatch II
Shared: RPG · Action Roguelike · Action

Hades
Shared: Action Roguelike · Action · Roguelite

UnderMine
Shared: Action Roguelike · RPG · Roguelite

20 Minutes Till Dawn
Shared: Action Roguelike · Bullet Hell · Roguelite

Nova Drift
Shared: Bullet Hell · Action Roguelike · Shoot 'Em Up

Nordic Ashes: Survivors of Ragnarok
Shared: Action Roguelike · Bullet Hell · Action RPG

Skul: The Hero Slayer
Shared: Action · Action Roguelike · Roguelite

Nuclear Throne
Shared: Action Roguelike · Action · Bullet Hell

Cultivation Story: Reincarnation
Shared: RPG · Action Roguelike · Action

Star of Providence
Shared: Action Roguelike · Bullet Hell · Roguelite

Sephiria
Shared: Action Roguelike · Roguelite · Action

I Am Legion: Stand Survivors
Shared: Action Roguelike · Bullet Hell · Roguelite

Heroes of Hammerwatch
Shared: Action Roguelike · Roguelite · RPG

Boneraiser Minions
Shared: Action Roguelike · Bullet Hell · Roguelite

Enter the Gungeon
Shared: Action Roguelike · Bullet Hell · Pixel Graphics

Conquest Dark
Shared: Action · Action RPG · Action Roguelike