Games like Atomcraft
Games like Atomcraft include Terraria, Kenshi, Rust, Don't Starve Together, and Kerbal Space Program. We matched them by the tags players give Atomcraft on Steam (Sandbox, Crafting, Science, Simulation, and Survival): closest matches first, and among equally close ones the better-known games.

Terraria
Shared: Sandbox · Survival · Crafting

Kenshi
Shared: Sandbox · Survival · Crafting

Rust
Shared: Crafting · Survival · Sandbox

Don't Starve Together
Shared: Survival · Crafting · Sandbox

Kerbal Space Program
Shared: Sandbox · Simulation · Science

Scrap Mechanic
Shared: Sandbox · Survival · Crafting

Project Zomboid
Shared: Survival · Sandbox · Crafting

Core Keeper
Shared: Survival · Sandbox · Crafting

The Forest
Shared: Crafting · Survival · Sandbox

Don't Starve
Shared: Crafting · Survival · Sandbox

ARK: Survival Ascended
Shared: Survival · Crafting · Sandbox

Starbound
Shared: Sandbox · Survival · Crafting

Conan Exiles Enhanced
Shared: Survival · Crafting · Sandbox

Space Engineers
Shared: Sandbox · Simulation · Survival

Enshrouded
Shared: Survival · Crafting · Open World

Graveyard Keeper
Shared: Crafting · Sandbox · Simulation

Stardew Valley
Shared: Sandbox · Simulation · Crafting

Forager
Shared: Crafting · Survival · Sandbox

Noita
Shared: Sandbox · Physics · Simulation

Palworld
Shared: Survival · Crafting · Sandbox

Raft
Shared: Survival · Crafting · Sandbox

ARK: Survival Evolved
Shared: Survival · Crafting · Sandbox

Craftopia
Shared: Crafting · Sandbox · Survival

People Playground
Shared: Sandbox · Physics · Simulation