Torchlight II fan, you've got GUTS now. As does the rest of the community. The game's latest patch doesn't just add new armor sets, pets, and tilesets, it also adds the game's primary modding tool known as GUTS. And this isn't just a halfhearted implementation, as the modding functionality extends through the game to the very core.
Playing the game through Steam? It's integrated through Steam Workshop. Want to play a multiplayer game with your favorite mod? There's full multiplayer support and the ability to see which mods are enabled in a given game. Want to start modding but have no idea where to start? There's a whole wiki filled with documentation on how to get started.
Don't own the game but love the idea of modding a multiplayer game? That's cool, too. The game is on sale until April 8th for $9.99 to celebrate the release of the modding tools. So if this sort of thing tickles your fancy, you've got almost no reason not to check it out.