Geralt deserved a restful retirement to the peaceful vinyard life after his final adventures in The Witcher 3: Blood & Wine, but who said that really had to be the end? Modder memr clearly wasn't ready for The Witcher 3 to be over and done with, as they've released a new project, called Radish Modding Tools, which is "a collection of in-game mods and external tools aimed to enable the creation of new quests by mod authors."
The Witcher 3 doesn't have an especially active mod scene these days, and most of the best Witcher 3 mods focus on overhauling combat or making quality of life changes. That's partially because the official mod tools were disappointingly limited compared to The Witcher's and The Witcher 2's.
These new Radish Modding Tools can't replace a powerful toolset from CD Projekt, but should be a lot better than nothing. As memr writes, "Although only a smallish subset of all possible features is supported it *should* allow to create non-trivial, story-based quests—just don't expect clicky-pointy-done workflows."
Radish Modding Tools is still a work-in-progress, and memr writes that "The tools will be updated/published as a package once the most pressing bugs are worked out." In the meantime, there's an example mod on the Nexus that shows what the tools are capable of. Memr built a new area for Geralt to travel to, and the mod shows off Radish's ability to create in-engine cutscenes.
Memr elaborates a bit in the mod's comments: You can't create or import new animations with Radish, but you can create new terrain. And you can use all the game's existing animations, which is a hell of a library already.
"The most difficult aspects for 'real' quests will be the actual planning and laying out of the quest," memr writes. "I can create a go-there-pickup-n-of-generic-thingie-bring-it-back-sprinkled-with-generic-attacking-monsters quest without scenes on vanilla hubs in a weekend—but that would be a pointless, generic quest, wouldn't it?"
If you're not the mod-making type, but hope to see some new quests trickle out of the modding community a few months from now, keep an eye on Nexusmods' Witcher 3 Quests and Adventures category.
Below I've included a few screenshots of the mod tools in action.