Being far beneath the surface tends to make for rather cramped quarters. Instead of rolling hills or flat plains, you have various tunnels and passages you must make your way through. These can be rather dangerous places, and in Warcry: Catacombs, they have their own special rules called the Tunnels of Death rules. We get a preview of them in this article.
From the article:
Get ready to take the fight underground! Warcry: Catacombs introduces a swathe of new rules – known collectively as the Tunnels of Death rules – designed for staging exciting dungeon battles. Today, we’re looking at some of the abilities and dungeon features that add a new, narrative-driven dimension to the gameplay in every battle you fight.