Jeff Wilcke made commits to obscuren/mutan between 23rd March 2014 and 7th July 2015.
The deprecation was just weeks before the mainnet Frontier launch.
mutan
Mutan was a smart contract language that was created by Jeff Wilcke in the early part of 2014. It was originally called HLL (high level language). As Solidity matured, Mutan was deprecated.