As much as the name suggests that this could be an elaborate joke from Runic Games, rest assured, the new game editor for Torchlight II is very real.
In a post on their blog, Runic announced the release of the GUTS update, which adds a game editor to the game that adds a whole other level of customization such as in item and skill balance, level layouts, quests, and many other areas.
"GUTS is the new version of our content editor we used to create all the content for Torchlight II. We use it to make most things in the game – Levels, skills, classes, monsters, items, spawn classes, balance curves, UI, etc," said Tools Engineer Greg Brown in a Q&A. "We started this project with 'TorchED' which was used for Torchlight, but we've made a large number of improvements and additions for GUTS."
GUTS also allows players to share mods online in a launcher. It is also fully supports Steam Workshop. which allows players to synchronize any previously-subscribed mods, and publish mods to the workshop.
Runic also added tons of new content, including the NetherRealm tileset, which features new dungeons, new monsters, armorsets, and new pets including the Headcrab.
To reiterate, no part of this is a joke as far as we know, especially the Headcrab.
If you want to learn more about the update, you can read more of the Q&A, also with Art Director Jason Beck and Lead Level Designer Patrick Blank, on Runic's website.