Not really a successor, but as the poster above said, a cousin.
This lineage of open-source games started from Total Annihilation, which had a lot of mods that ran into engine limitations. This resulted in a bunch of enterprising open-sourced devs to develop a compatible engine, without those limitations. This engine (Spring Engine) has then evolved into something much more impressive and capable. Zero-K was implemented on this engine. Beyond All Reason uses the Recoil engine, which is a fairly recent for of Spring.
This lineage of open-source games started from Total Annihilation, which had a lot of mods that ran into engine limitations. This resulted in a bunch of enterprising open-sourced devs to develop a compatible engine, without those limitations. This engine (Spring Engine) has then evolved into something much more impressive and capable. Zero-K was implemented on this engine. Beyond All Reason uses the Recoil engine, which is a fairly recent for of Spring.