I'm not into this myself for rp, but what if you guys themed it off of Dwarf Fortress in some way?
Dwarf Fortress is already amazing at making stories all by itself and you literally NEED liquor to keep them sane. They don't even need to drink water so long as they have liquor.
Maybe this tavern hides an entire dwarves fortress that brews all sorts of stuff, and the tavern is a front for their 'illicit wares'.