This article proposes a novel approach towards quick concept generation and validation of interactive-product behaviours. When designing for user-product interactions, designers have to consider spatial and behavioural elements besides form/tangible aspects and perform quick-validation of the generated concepts often done through functional prototyping at later design stages. As a result, the designed-outcomes often depend on parameters like designer’s familiarity with the design tools used, the level of fidelity achieved while prototyping and the frequency of design-iterations, limiting a thorough-exploration of concept-space and outcomes’ creativity at the early design stages. This research targets such dependencies and non-creative hindrances at concept generation stage through a Mixed Reality implementation. This work establishes requirements for creating a suitable design-tool and presents a proof-of-concept use-case. A design task to ideate, create and revise concepts of playful product-behaviours swiftly was performed to assess the impact of the implemented method. In an empirical study, a broader exploration of solution-space and an overall improvement in creative output-flow was observed when compared to the design-outcomes in the traditional storyboard design approach. Though the implemented design-tool’s unfamiliarity and capability presented a challenge, a significant increase in usage of iterative concept-design behaviour was observed throughout the study.