Presenting and Evaluating Smart2: A Bidirectional Real-Time Input Framework for Smartphone–Smartwatch Videogames

Smartwatches offer new opportunities for extending mobile gameplay through wearable input, but their integration into real-time game interactions requires communication frameworks capable of maintaining low and stable latency. This study evaluates Smart2, a smartwatch–smartphone communication module designed to integrate Wear OS input into Unity-based mobile games. The framework was evaluated through five minigames implementing Tap, D-Pad, Hold, Joystick, and motion-based input. A quantitative latency evaluation was conducted across five Android smartphones using a Samsung Galaxy Watch 7 as the smartwatch input device. Latency was estimated through a round-trip time approach and reported as estimated one-way latency. Results showed stable connectivity and no observed message loss, as verified through sequential event identifiers and their corresponding acknowledgments. A two-factor main-effects ANOVA showed statistically significant differences in mean estimated one-way latency between the five experimental tests and between minigames, indicating variability in the evaluated test conditions and interaction modalities. These findings suggest that Smart2 can support real-time smartwatch-based interaction in Unity gameplay while highlighting the importance of evaluating latency in relation to both test conditions and interaction design.