Keep the core beats fixed, and let the choices only shift sub‑threads that feed back into those beats. Map each choice to a single pivot point—an event, a character reaction, or a small world change—so the plot never splinters. Use modular scenes that can be swapped without altering the main timeline, and always end every branch at a converging node that restores the narrative to the same structural spot. That way the story stays tight, but the player still feels that their decisions mattered.