Just in case this game got lost amidst the survival sandbox crowd, Stars End is a survival MMO with a decidedly Firefly vibe to it. It hit early access this past fall and has been releasing a number of updates ever since including a new character and vehicle system, new tutorial and town redesigns, and reworked mounts.
Content retrieved from: https://massivelyop.com/2020/03/04/survival-sandbox-stars-ends-latest-update-promises-to-significantly-improve-performance/.