While the idea of a medival version of Rust with fantasy game elements was appealing, Ruin never really managed to escape Rust's shadow enough to define its own gameplay.
Ruin had elements that were mostly identical to Rust (crafting, looting, harvesting), and the features that set it apart from Rust were problematic. The huge hand crafted world would have needed constant expanding and updating to keep players interested. The missions would get repetative and boring unless we constantly added new ones. That isn't something we've got the bandwidth or stamina for.
It's also easy to see that the game would fall into a lot of the same development pitfalls as Rust. Server DDOSing, cheating, hostile & toxic community - why would we want two of those?