Found this one lately: BAR (Beyond All Reason)
open source, free, based on an engine (spring) which aims to reborn Total Annihilation.
trailer : https://youtu.be/8K_fSWfOC1w?si=a7DHk-tbekJV0JfP
starter guide : https://youtu.be/H_00sBprHzU?si=tzTcCNWWJh7pcXD5