Looks like someone’s delved too deep! Sometimes, in the life of a Dwarf, you reach a point in your life where you begin to question some of your past decisions. This blue dwarf in the screenshot has just reached one of those points…
This conga train of goblin violence wasn’t a code error, just a combination of level design and player cruelty. Each level has three strata: dirt, stone and the deep. Each turn you get to place a section of tunnel, and you can put it anywhere, including portions of the tunnel not anywhere near you. Digging downwards is the best way to make the money you need to win, but the deeper you go, the less safe you are. And unfortunately for Blue, you can also “help” someone out by connecting their tunnels to monster-filled tunnels before they’re ready.
And since monsters get aggressive towards Dwarfs that get too close to their treasures, opening a tunnel close to a rival can help steer hordes of monsters in their direction. Since monsters can spawn anywhere, and they’re more dangerous in the deep, dark depths of the mine, the first person to breach the Deep layer often gets a nasty surprise. That’s what happened here.
The monsters usually come in waves, as the nearest or fastest group reaches the new opening first and look for a Dwarf to attack. If these groups meet resistance they can pile up like this, and the density of their population can quickly get out of control. If Blue had a fighter or two defending those lower tunnels, this never would have happened! You’ll want to consider your strategy when you pick your five dwarf types. You don’t have to fight monsters to win, and you can always make your rivals fight them for you.