Runic Games has just launched an updated version of Torchlight 2, which now fully supports Steam Workshop for easily creating, sharing, and downloading custom maps, levels, items, skills, gameplay, and much more. Additionally, Runic Games has released their own in-house development tool, GUTS, which is fully integrated with the Workshop. Using these tools, you can publish directly to Steam Workshop, making it available immediately for others to play. More details and specifics are below.
Runic has worked to make the process as seamless as possible, with a focus on allowing modded multiplayer games with a minimum of fuss. When playing Internet games in the lobby, you will be able to filter modded games by mod combination, and with a single button click, subscribe to those mods. Torchlight 2 will then restart, synchronize them, and activate them before returning you to the game.
A new launcher synchronizes any mods you have subscribed to, and lets you customize their activation state and loading priority. When playing modded games, you can view your mod history, any previously played mods, and see the potential impact that disabling mods may have on your character.
The GUTS editor also converts pre-GUTS mods into the official mod format, with an eye toward making the transition much easier for ambitious early modders.