Games like Momentum Mayhem
Games like Momentum Mayhem include Poly Bridge, Kerbal Space Program, Garry's Mod, Poly Bridge 2, and Hozy. We matched them by the tags players give Momentum Mayhem on Steam (Puzzle, Sandbox, Building, Education, and Science): closest matches first, and among equally close ones the better-known games.

Poly Bridge
Shared: Building · Puzzle · Sandbox

Kerbal Space Program
Shared: Sandbox · Science · Physics

Garry's Mod
Shared: Sandbox · Building · Physics

Poly Bridge 2
Shared: Puzzle · Building · Sandbox

Hozy
Shared: Sandbox · Puzzle · Casual

Bridge Constructor Portal
Shared: Puzzle · Building · Physics

PC Building Simulator
Shared: Education · Building · Sandbox

Besiege
Shared: Sandbox · Building · Physics

Crazy Machines 3
Shared: Puzzle · Sandbox · Physics

while True: learn()
Shared: Puzzle · Education · Building

Universe Sandbox
Shared: Sandbox · Physics · Science

Poly Bridge 3
Shared: Puzzle · Building · Physics

Townscaper
Shared: Building · Sandbox · Casual

People Playground
Shared: Sandbox · Physics · Building

Kerbal Space Program 2
Shared: Sandbox · Building · Science

Space Engineers
Shared: Sandbox · Building · Physics

Brick Rigs
Shared: Sandbox · Building · Physics

House Flipper
Shared: Building · Sandbox · Simulation

Planet Coaster
Shared: Building · Sandbox · Simulation

Scribblenauts Unlimited
Shared: Puzzle · Sandbox · Casual

Tiny Glade
Shared: Building · Sandbox · Casual

The Sims™ 4
Shared: Building · Sandbox · Simulation

Universe Sandbox
Shared: Sandbox · Science · Education

Cities: Skylines
Shared: Building · Sandbox · Simulation