Games like GearBlocks
Games like GearBlocks include BeamNG.drive, Garry's Mod, Brick Rigs, People Playground, and Car Mechanic Simulator 2018. We matched them by the tags players give GearBlocks on Steam (Building, Physics, Simulation, Sandbox, and Moddable): closest matches first, and among equally close ones the better-known games.

BeamNG.drive
Shared: Simulation · Physics · Driving

Garry's Mod
Shared: Sandbox · Physics · Building

Brick Rigs
Shared: Building · Sandbox · Physics

People Playground
Shared: Physics · Sandbox · Moddable

Car Mechanic Simulator 2018
Shared: Simulation · Building · Automobile Sim

Besiege
Shared: Simulation · Physics · Sandbox

Space Engineers
Shared: Building · Sandbox · Simulation

Kerbal Space Program
Shared: Simulation · Physics · Sandbox

My Summer Car
Shared: Simulation · Automobile Sim · Building

CarX Drift Racing Online
Shared: Simulation · Sandbox · Moddable

Car Mechanic Simulator 2021
Shared: Simulation · Sandbox · Automobile Sim

Scrap Mechanic
Shared: Building · Sandbox · Physics

Teardown
Shared: Physics · Sandbox · Destruction

Wreckfest
Shared: Simulation · Destruction · Physics

Euro Truck Simulator 2
Shared: Simulation · Driving · Moddable

Assetto Corsa
Shared: Simulation · Automobile Sim · Driving

Mon Bazou
Shared: Sandbox · Automobile Sim · Building

Goat Simulator
Shared: Simulation · Physics · Sandbox

American Truck Simulator
Shared: Simulation · Automobile Sim · Driving

SnowRunner
Shared: Simulation · Automobile Sim · Driving

Turbo Dismount™
Shared: Physics · Simulation · Destruction

City Car Driving
Shared: Simulation · Automobile Sim · Driving

Stormworks: Build and Rescue
Shared: Building · Sandbox · Physics

RoadCraft
Shared: Building · Simulation · Physics