The Tavern

Bats. Bats bat bats. Replace everything with bats. Goblins? Bats. Jackals? More bats. Orcs? Orcbats. Make a new type of bat for every enemy. Use the same sprite over and over so people have a hard time telling what kind is which until the elemental ones start showing up. Hydras? Bats with many heads. Dragons? Bats with breath weapons. Draconians? MORE BATS DON'T YOU GET IT.

And every single enemy has the bat AI of dancing around you like crazy, to make every single melee-based character's life a living hell.

Oh and change all the permafood to different kinds of bats too. Fruitbats. Honeybats. Meatbats. Breadbats.

Let's go a step further and make it so bows and crossbows fire batarrows and batbolts. Batswords, batdaggers, batshields. All the bats.

And the only unrands ever to spawn are, of course, pieces of Batman's armor.

All thrown weapons replaced with batarangs?

I'd bat that this is a bat idea. You'd batter go to your bat and sleep.