Games like Slordax: The Unknown Enemy
Games like Slordax: The Unknown Enemy include BALL x PIT, Planes, Bullets and Vodka, Hotline Miami 2: Wrong Number, Hotline Miami, and 20 Minutes Till Dawn. We matched them by the tags players give Slordax: The Unknown Enemy on Steam (Action, Shoot 'Em Up, Retro, Top-Down Shooter, and Pixel Graphics): closest matches first, and among equally close ones the better-known games.

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

Planes, Bullets and Vodka
Shared: Action · Shoot 'Em Up · Retro

Hotline Miami 2: Wrong Number
Shared: Action · Pixel Graphics · Retro

Hotline Miami
Shared: Action · Pixel Graphics · Retro

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

DoDonPachi Resurrection
Shared: Shoot 'Em Up · Top-Down Shooter · Action

Earthion
Shared: Action · Shoot 'Em Up · Retro

LUFTRAUSERS
Shared: Action · Bullet Hell · Shoot 'Em Up

Sky Force Reloaded
Shared: Shoot 'Em Up · Top-Down Shooter · Action

Cyberhunt
Shared: Action · Shoot 'Em Up · Retro

UBERMOSH Vol.5
Shared: Action · Retro · Pixel Graphics

ZeroRanger
Shared: Shoot 'Em Up · Action · Bullet Hell

Bit Blaster XL
Shared: Shoot 'Em Up · Bullet Hell · Action

DEVIL BLADE REBOOT
Shared: Shoot 'Em Up · Action · Pixel Graphics

Warhammer 40,000: Boltgun
Shared: Retro · Action · Pixel Graphics

Angel at Dusk
Shared: Action · Bullet Hell · Pixel Graphics

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

Halo: Spartan Assault
Shared: Action · Top-Down Shooter · Top-Down

Nuclear Throne
Shared: Pixel Graphics · Action · Bullet Hell

Revolution Ace
Shared: Action · Shoot 'Em Up · Bullet Hell

Crimzon Clover World EXplosion
Shared: Action · Shoot 'Em Up · Bullet Hell

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

Deep Rock Galactic: Survivor
Shared: Top-Down Shooter · Bullet Hell · Action

Half-Life
Shared: Action · 1990's · Aliens