Games like The Chaos Engine
Games like The Chaos Engine include METAL SLUG 3, DOOM + DOOM II, METAL SLUG X, Broforce, and METAL SLUG. We matched them by the tags players give The Chaos Engine on Steam (Action, Retro, Top-Down, Classic, and Shooter): closest matches first, and among equally close ones the better-known games.

METAL SLUG 3
Shared: Action · Co-op · Retro

DOOM + DOOM II
Shared: Action · Retro · Classic

METAL SLUG X
Shared: Action · Co-op · Retro

Broforce
Shared: Action · Co-op · 2D

METAL SLUG
Shared: Action · Retro · Co-op

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

Quake
Shared: Action · Classic · Shooter

Sonic Mania
Shared: Retro · 2D · Classic

Contra Anniversary Collection
Shared: Action · Retro · Classic

DOOM 64
Shared: Action · Retro · Classic

Cuphead
Shared: Co-op · 2D · Local Co-Op

METAL SLUG XX
Shared: Action · Retro · 2D

METAL SLUG 2
Shared: Action · Retro · 2D

Door Kickers: Action Squad
Shared: Retro · Action · Shooter

Half-Life: Opposing Force
Shared: Action · Classic · Shooter

Left 4 Dead 2
Shared: Co-op · Action · Shooter

Quake II
Shared: Action · Classic · Shooter

STAR WARS™ Battlefront II (Classic, 2005)
Shared: Action · Classic · Shooter

Half-Life 2
Shared: Action · Classic · Shooter

Revolution Ace
Shared: Action · Shooter · Top-Down

Duke Nukem 3D: 20th Anniversary World Tour
Shared: Action · Classic · Retro

Planes, Bullets and Vodka
Shared: Action · Retro · Shooter

Halo: The Master Chief Collection
Shared: Classic · Co-op · Action

Call of Duty®
Shared: Action · Shooter · Singleplayer