Games like Entropy
Games like Entropy include Warhammer 40,000: Boltgun, POSTAL: Brain Damaged, Hotline Miami 2: Wrong Number, Hotline Miami, and BALL x PIT. We matched them by the tags players give Entropy on Steam (Boomer Shooter, Top-Down Shooter, Shoot 'Em Up, Shooter, and Action-Adventure): closest matches first, and among equally close ones the better-known games.

Warhammer 40,000: Boltgun
Shared: Boomer Shooter · Shooter · Action

POSTAL: Brain Damaged
Shared: Boomer Shooter · Shooter · Action

Hotline Miami 2: Wrong Number
Shared: Action · Pixel Graphics · Top-Down

Hotline Miami
Shared: Action · Top-Down · Pixel Graphics

BALL x PIT
Shared: Action · Shoot 'Em Up · Top-Down Shooter

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

Cyberhunt
Shared: Shoot 'Em Up · Action · 2D

12 is Better Than 6
Shared: Top-Down Shooter · Shooter · Action

Bot Vice
Shared: Top-Down Shooter · Shoot 'Em Up · Action-Adventure

Turbo Overkill
Shared: Boomer Shooter · Shooter · Action

Huntdown
Shared: Shooter · Shoot 'Em Up · Action

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

Bit Blaster XL
Shared: Shoot 'Em Up · Shooter · 2D

Broforce
Shared: Action · 2D · Pixel Graphics

Escape From Duckov
Shared: Top-Down Shooter · Action · Shooter

Zombotron
Shared: Action · 2D · Shooter

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

SANABI
Shared: Action · Pixel Graphics · 2D

DUSK
Shared: Boomer Shooter · Shooter · Action

Insect Swarm
Shared: Shooter · Shoot 'Em Up · Top-Down Shooter

Selaco
Shared: Shooter · Boomer Shooter · Action

ZeroRanger
Shared: Shoot 'Em Up · Action · Shooter

CULTIC
Shared: Boomer Shooter · Shooter · Action

Quake II
Shared: Boomer Shooter · Shooter · Action