The RPG Larian made before Baldur's Gate 3 included an extensive mod development kit which could be used to build whole new campaigns with custom maps and NPCs and quests—something like Bethesda's Skyrim Creation Kit. It's part of the reason I voted to make Divinity: Original Sin 2 our 2017 Game of the Year, but sadly, the complicated, crash-prone tools didn't lead to a thriving custom campaign scene for Original Sin 2.
For that and other reasons, we shouldn't expect the forthcoming Baldur's Gate 3 mod tools to be as comprehensive as those Divinity Engine tools, Larian boss Swen Vincke has indicated.
"With Divinity, there was not a lot of traction on [making custom campaigns], just because it's so much work," said Vincke in an interview with PC Gamer at GDC this week. "And also, our tools are very complicated. So we're going to focus on things that we know a lot of people want to mod and we're going to try to make that process easier. Not all tools are going to be shipped, because we wouldn't be able to support them."
That said, "quite a bunch of things" will be moddable with the tools, Vincke said. He also hopes the Baldur's Gate 3 tools will be easier to use than the Divinity tools, which he called "a bit shaky." (I did my best to make a custom map in The Divinity Engine 2, but eventually gave up, in part because of frequent crashes.)
"We are a game development company, we're not a tools company," said Vincke. "So the tools are really for internal use. And so we're sharing them with the audience."
The CEO didn't detail exactly what Baldur's Gate 3 mod tools to expect, but I'd guess that modders will find it easier to do what they're already doing: adding and tweaking 3D models, textures, items, spells, and abilities. (And introducing Thomas the Tank Engine in new ways, perhaps.) The official mod support will also allow console players to install Baldur's Gate 3 mods for the first time, which has made the project "complicated" because of the multiple parties involved, Vincke said.
Although it will continue to update Baldur's Gate 3, Larian announced this week that it's ending its relationship with D&D owner Wizards of the Coast and won't be making Baldur's Gate 3 DLC or a sequel.
"We are a company of big ideas. We are not a company that's made to create DLCs or expansions," Vincke said during a GDC talk. "We tried that actually, a few times. It failed every single time. It's not our thing. Life is too short. Our ambitions are very large."
Expanding the RPG is now up to the players, then. Baldur's Gate 3's official mod support doesn't have a release date, but Vincke hopes the tools will be with us in the "not so distant future."