The specific version you're asking about, from 2021, likely included several enhancements and bug fixes over its predecessors. As with any software, updates typically aim to improve stability, add features, and refine user experience.
The 2021 updates likely included new features that enhanced gameplay and the simulation's educational value. Features such as improved planetary and stellar evolution models, better handling of galaxy interactions, and possibly more tools for creating custom scenarios.
The groundwork laid in 2021 eventually led to the massive graphics and physics overhauls seen in the v34 and v35 updates. For players looking to run the most recent versions of the game, Steam requirements now specify a graphics card compatible with as of March 2025.
You can now manually set the temperature and pressure limits for where vegetation and city lights appear on a planet. Atmosphere Optimization: