Games like One Million Worlds
Games like One Million Worlds include Wobbly Life, Trove, The Scroll of Taiwu : Beyond The Dome, Terraria, and Goat Simulator. We matched them by the tags players give One Million Worlds on Steam (Indie, Early Access, Sandbox, Voxel, and Open World): closest matches first, and among equally close ones the better-known games.

Wobbly Life
Shared: Sandbox · Adventure · Open World

Trove
Shared: Sandbox · Voxel · Open World

The Scroll of Taiwu : Beyond The Dome
Shared: Sandbox · Indie · Open World

Terraria
Shared: Sandbox · Adventure · Indie

Goat Simulator
Shared: Sandbox · Open World · Indie

Scrap Mechanic
Shared: Sandbox · Open World · Building

Totally Accurate Battle Simulator
Shared: Sandbox · Indie · Simulation

Garry's Mod
Shared: Sandbox · Casual · Building

Kerbal Space Program
Shared: Sandbox · Simulation · Indie

Stardew Valley
Shared: Sandbox · Indie · Pixel Graphics

Paralives
Shared: Indie · Open World · Sandbox

Space Engineers
Shared: Sandbox · Open World · Simulation

Teardown
Shared: Sandbox · Voxel · Indie

Slime Rancher
Shared: Adventure · Open World · Sandbox

Noita
Shared: Indie · Sandbox · Open World

Feed and Grow: Fish
Shared: Early Access · Indie · Simulation

People Playground
Shared: Sandbox · Simulation · Physics

A Game About Digging A Hole
Shared: Sandbox · Voxel · Simulation

LEGO® Worlds
Shared: Sandbox · Open World · Adventure

Empyrion - Galactic Survival
Shared: Simulation · Open World · Sandbox

My Time at Portia
Shared: Open World · Casual · Adventure

BeamNG.drive
Shared: Sandbox · Simulation · Open World

7 Days to Die
Shared: Open World · Voxel · Sandbox

Brick Rigs
Shared: Sandbox · Open World · Early Access