Games like X4: Timelines
Games like X4: Timelines include X4: Foundations, Elite Dangerous, Kerbal Space Program, X Rebirth, and Avorion. We matched them by the tags players give X4: Timelines on Steam (Sandbox, Space Sim, Economy, Trading, and Space): closest matches first, and among equally close ones the better-known games.

X4: Foundations
Shared: Space Sim · Space · Sandbox

Elite Dangerous
Shared: Space Sim · Space · Exploration

Kerbal Space Program
Shared: Sandbox · Space · Space Sim

X Rebirth
Shared: Space Sim · Space · Sandbox

Avorion
Shared: Sandbox · Space Sim · Exploration

Stellaris
Shared: Space · Sandbox · Strategy

EVE Online
Shared: Space Sim · Exploration · Space

Cities: Skylines
Shared: Sandbox · Building · Simulation

Jurassic World Evolution
Shared: Sandbox · Building · Simulation

Space Engineers
Shared: Sandbox · Space · Building

X3: Terran Conflict
Shared: Sandbox · Space · Space Sim

Kerbal Space Program 2
Shared: Sandbox · Space · Building

Planet Coaster
Shared: Sandbox · Building · Simulation

Jurassic World Evolution 2
Shared: Sandbox · Building · Simulation

Dyson Sphere Program
Shared: Space · Building · Sandbox

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

Starminer
Shared: Sandbox · Space Sim · Economy

Supermarket Simulator
Shared: Economy · Simulation · Trading

Cities: Skylines II
Shared: Sandbox · Building · Economy

Empyrion - Galactic Survival
Shared: Space · Simulation · Space Sim

Manor Lords
Shared: Sandbox · Strategy · Simulation

Hardspace: Shipbreaker
Shared: Space · Sandbox · Simulation

Spaceflight Simulator
Shared: Sandbox · Space Sim · Space

Planet Zoo
Shared: Sandbox · Building · Economy