Designing for Immersion: A Cross-Platform Evaluation Framework for XR Heritage Storytelling

As immersive media increasingly mediate cultural heritage experiences, a key challenge is how to evaluate content deployed across diverse Extended Reality (XR) platforms. This paper proposes a three-Axis evaluation framework-Interpretive, Cognitive/Perceptual, and Affective/Sensory-That synthesizes constructs from museum studies, Human Computer Interaction (HCI), and presence theory into a comparative structure. The framework is applied to "Who Killed Helene Pumpulivaara?", a narrative experience produced in both WebXR and Virtual Reality (VR) formats, with a Spatial Augmented Reality (SAR) version underway. Using user feedback from pilot workshops and AI-Assisted design workflows, the study identifies how platform affordances reshape meaning, usability, and emotional impact. The resulting matrix supports transparent, design-grounded evaluation and offers transferable insights for XR storytelling across modalities.