Games like Happy Lab
Games like Happy Lab include BONEWORKS, PC Building Simulator, BONELAB, Internet Cafe Simulator 2, and GoreBox. We matched them by the tags players give Happy Lab on Steam (Action, Simulation, Puzzle, Sandbox, and Immersive Sim): closest matches first, and among equally close ones the better-known games.

BONEWORKS
Shared: Action · Sandbox · Puzzle

PC Building Simulator
Shared: Simulation · Immersive Sim · Sandbox

BONELAB
Shared: Action · Sandbox · First-Person

Internet Cafe Simulator 2
Shared: Simulation · 3D · Sandbox

GoreBox
Shared: Sandbox · First-Person · 3D

Portal
Shared: Puzzle · First-Person · Action

Car Mechanic Simulator 2021
Shared: Simulation · Sandbox · 3D

Totally Accurate Battle Simulator
Shared: Simulation · Sandbox · Action

Garry's Mod
Shared: Sandbox · Simulation · First-Person

House Flipper
Shared: Simulation · Sandbox · Action

IRON NEST: Heavy Turret Simulator
Shared: Simulation · Action · 3D

Prey
Shared: Immersive Sim · Sci-fi · Action

Hardspace: Shipbreaker
Shared: Simulation · Sandbox · Puzzle

The Forest
Shared: Action · Horror · First-Person

Nuclear Option
Shared: Simulation · Action · 3D

Half-Life 2
Shared: Action · Sci-fi · First-Person

Arma 3
Shared: Action · Simulation · First-Person

Poppy Playtime
Shared: Puzzle · Horror · First-Person

The Exit 8
Shared: Puzzle · Immersive Sim · Horror

Resident Evil 7 Biohazard
Shared: First-Person · Horror · Action

Black Mesa
Shared: Action · First-Person · Sci-fi

System Shock
Shared: Action · Immersive Sim · Sci-fi

Buckshot Roulette
Shared: First-Person · Horror · 3D

People Playground
Shared: Sandbox · Simulation · Action