Games like Tiny Pixel Planets
Games like Tiny Pixel Planets include Terraria, No Man's Sky, Avorion, Starbound, and Kerbal Space Program. We matched them by the tags players give Tiny Pixel Planets on Steam (Exploration, Side Scroller, Sandbox, Building, and Crafting): closest matches first, and among equally close ones the better-known games.

Terraria
Shared: Sandbox · Exploration · Crafting

No Man's Sky
Shared: Exploration · Space · Sandbox

Avorion
Shared: Exploration · Sandbox · Building

Starbound
Shared: Sandbox · Space · Crafting

Kerbal Space Program
Shared: Sandbox · Space · Building

Kerbal Space Program 2
Shared: Exploration · Sandbox · Space

EVE Online
Shared: Exploration · Space Sim · Space

Spaceflight Simulator
Shared: Sandbox · Exploration · Space

Empyrion - Galactic Survival
Shared: Space · Exploration · Building

Core Keeper
Shared: Exploration · Sandbox · Crafting

Space Engineers
Shared: Sandbox · Building · Space

Elite Dangerous
Shared: Exploration · Space · Space Sim

ASTRONEER
Shared: Exploration · Space · Sandbox

The Forest
Shared: Crafting · Building · Exploration

Satisfactory
Shared: Crafting · Building · Exploration

X4: Foundations
Shared: Exploration · Space · Sandbox

Valheim
Shared: Building · Exploration · Crafting

SPORE™
Shared: Sandbox · Exploration · Space

Dune: Awakening
Shared: Exploration · Sandbox · PvE

Rust
Shared: Crafting · Building · Sandbox

Keplerth
Shared: Exploration · Sandbox · Building

Once Human
Shared: Exploration · Building · Crafting

V Rising
Shared: Crafting · Building · PvE

ICARUS
Shared: Exploration · Crafting · Building