Games like Euclid's Inferno
Games like Euclid's Inferno include Halo: Spartan Assault, Escape From Duckov, 12 is Better Than 6, BioShock Infinite, and Grand Theft Auto V Legacy. We matched them by the tags players give Euclid's Inferno on Steam (Action, Top-Down Shooter, Isometric, Singleplayer, and Minimalist): closest matches first, and among equally close ones the better-known games.

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

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

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

BioShock Infinite
Shared: Action · Shooter · Singleplayer

Grand Theft Auto V Legacy
Shared: Action · Shooter · Singleplayer

BALL x PIT
Shared: Action · Top-Down Shooter · Arcade

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

God of War
Shared: Action · Singleplayer · Adventure

Wolcen: Lords of Mayhem
Shared: Isometric · Singleplayer · Action

Half-Life 2
Shared: Action · Singleplayer · Shooter

Alien Shooter
Shared: Action · Shooter · Singleplayer

Red Dead Redemption 2
Shared: Action · Singleplayer · Adventure

Tomb Raider Game of the Year
Shared: Action · Singleplayer · Adventure

Black Myth: Wukong
Shared: Action · Singleplayer · Mythology

Shadowgrounds
Shared: Top-Down Shooter · Action · Singleplayer

Snake Force
Shared: Action · Top-Down Shooter · Shooter

Rise of the Tomb Raider™
Shared: Action · Singleplayer · Adventure

American Fugitive
Shared: Action · Top-Down Shooter · Adventure

Exit the Gungeon
Shared: Action · Arcade · Singleplayer

Just Cause™ 3
Shared: Action · Singleplayer · Shooter

Halo: Spartan Strike
Shared: Action · Top-Down Shooter · Singleplayer

RUINER
Shared: Action · Top-Down Shooter · Isometric

Far Cry 3
Shared: Action · Shooter · Adventure

Intravenous 2
Shared: Shooter · Action · Singleplayer