Head-mounted mixed reality (MR) often prioritises individual immersion, potentially drawing attention away from others sharing the room. This paper asks how MR can support co-located spatial dialogue through embodied interaction and activity visible to non-headset observers. We introduce Immersive Commons, a design framework, and Atmos Messages, a prototype combining gesture-based, ephemeral spatial messages with voice transcription, preset text, and a public floor-plan overview. Following a Research through Design approach, fifteen participants created 236 messages across two sessions, including 48 voice-authored messages. Questionnaire responses highlighted playfulness and social awareness, while observations suggested opportunities for exchange grounded in the architectural setting. Interaction clustered near the public display, although this was also where participants put on their headsets. These findings suggest the potential of ephemeral spatial messaging to support co-located exchange, with playfulness, shared visibility, and architectural context informing the design of more social and situated MR experiences.
Urban screens have become a global feature of the media city, yet their developmental paths are not universal. This paper argues that the evolution of urban screens in China constitutes a distinct paradigm of media urbanism, termed Chineseness, understood here not as cultural essence but as a relational, historically situated configuration of three linked elements: deep-rooted lineages of public communication; state-steered technological leapfrogging driven by industrial policy and mega-events; and a regulatory paradox that enables spectacular scale while tightening operational control. Drawing on a five-stage genealogy (1990-present), a chronology of representative screens, and five paradigmatic cases, the study shows how this configuration produces temporal-spatial compression, the coexistence of multiple technological generations, and privileges collective witnessing over device-centric interactivity. The paper contributes a documented genealogy of Chinese urban screens, develops temporal-spatial compression and collective witnessing as analytical tools for non-Western media ecologies, and positions Chineseness as a globally relevant alternative to market-led models of media architecture.