If you're looking for a creative writing tool that lets you steer the plot and direction of your story, Novelcrafter could be just the ticket. This full-featured writing environment includes a personal Wiki for recording story details, multiple writing modes and AI tools. You can use your own models or those from third-party services like OpenAI to handle context and prompts, so it's good for both planners and pantsers.
Another good choice is Subtxt, which uses AI to help you construct narrative structure and consistency. With tools like Narrative Agents, Subtxt Muse and Premise Builder, it can help you construct rich narratives and find gaps in your story. It's geared for screenwriters, novelists and playwrights, and can analyze your work to help you refine it while keeping your voice intact.
Sudowrite is another AI-powered writing assistant that can help you generate ideas, outline, write and edit. Its Describe, Story Bible and Feedback tools can help you be more creative and productive. With customizable modes and project management tools, Sudowrite is designed to improve both the writing process and the writing itself.
If you prefer a more collaborative approach, check out StoryNest.ai, which can handle multiple formats like interactive fiction and scripts. The service offers character creation, world-building tools, AI-assisted editing and collaboration tools. It's geared for building compelling stories and novels, so it should be good for whatever writing project you're on.