Hello again!
Giant creatures are a staple of generic fantasy worlds, and since Dwarf Fortress strives to generate worlds which are almost as generic as possible, we have giant versions of most real-world animals in the game. You can tack giant in front of almost anything. Sometimes, this can be trouble - the pandas in our game are just called 'pandas', but a more proper name for the real-world creature is 'giant panda', so that's why we have 'gigantic pandas' for the giant version instead. The same thing happened with the 'giant tortoise.'
The rule in Dwarf Fortress is that a giant creature should be at least as large as a black bear, even if it's a giant version of a small insect. As the real-world creatures approach black bear size, and then beyond, we apply a curve, so that the largest ones are only roughly twice as large in every dimension as their counterpart. Giant whales are very, very large, but they are just eight times as massive as a normal whale, rather than the kind of scaling you see when you go from a spider to a giant spider.
Here are some giant underground creatures:
The giant cave spider has been one of the more notorious DF creatures for many years. The paralyzing venom is quite serious, webs are nasty, it can spring from ambush, and it can also just bite dwarf-sized creatures into pieces. It is an enlarged version of the cave spider, which has a stunning venom (which is merely extremely annoying.) Giant rats are classic beings, of course. We also have large rats since it felt like there needed to be extra size gradations for ratdom.
I feel most bad about the poor giant moles that blunder into fortresses. The art doesn't make me feel better about it! Cave swallows are surprisingly colorful birds.
And here are some more modest creatures, a sample of small-but-not-too-small mammals:
As you can imagine, once we got up to a certain level of animal coverage in the game, it was important for us to get the two iconic monotremes in the game, and fortunately the community pulled through when they selected a few hundred animals to be added to the game back in 2009.
The platypus has poisonous spurs, as in real life, which can cause painful swelling. Perhaps your fortress would benefit by allowing a platypus person adventurer to become a resident monster slayer?
- Tarn