
Navigate to Properties > Local Files > Browse Local Files. If it can't find the game, from your Steam library, right click on Age of Empires II: HD Edition and click on Properties.


This Reddit thread gives detailed instructions on how to do it, but I will outline how to do it here, assuming you already have AoE2 HD installed on Steam: AoE2 HD can be played on Voobly, but you need to install the compatibility patch.
