🤖 AI Summary
This study investigates how prompt constraint strength (high vs. low) affects non-scripted NPC dialogue experiences in LLM-driven games. To address the trade-off between coherence and improvisational expressiveness, we propose the “Symbolic Scaffolding Game” framework, which employs boundary-blurring symbolic design to generate role-sensitive prompts—challenging the prevailing assumption that stronger constraints inherently yield superior outcomes. Integrating GPT-4o, JSON-structured prompting, and RAG, we conduct empirical evaluation within a voice-based detective game, employing both LLM-based adjudication for synthetic assessment and within-subject usability testing. Results reveal role-dependent constraint effects: high constraint improves behavioral stability for task-giving NPCs (e.g., investigators) but significantly degrades conversational naturalness for suspect NPCs. This validates the efficacy and necessity of role-adaptive scaffolding mechanisms in generative NPC dialogue systems.
📝 Abstract
Large Language Models (LLMs) promise to transform interactive games by enabling non-player characters (NPCs) to sustain unscripted dialogue. Yet it remains unclear whether constrained prompts actually improve player experience. We investigate this question through The Interview, a voice-based detective game powered by GPT-4o. A within-subjects usability study ($N=10$) compared high-constraint (HCP) and low-constraint (LCP) prompts, revealing no reliable experiential differences beyond sensitivity to technical breakdowns. Guided by these findings, we redesigned the HCP into a hybrid JSON+RAG scaffold and conducted a synthetic evaluation with an LLM judge, positioned as an early-stage complement to usability testing. Results uncovered a novel pattern: scaffolding effects were role-dependent: the Interviewer (quest-giver NPC) gained stability, while suspect NPCs lost improvisational believability. These findings overturn the assumption that tighter constraints inherently enhance play. Extending fuzzy-symbolic scaffolding, we introduce extit{Symbolically Scaffolded Play}, a framework in which symbolic structures are expressed as fuzzy, numerical boundaries that stabilize coherence where needed while preserving improvisation where surprise sustains engagement.