This reports the graduation project aimed to investigate the occurrence of rebellious play through the X-eo prototype. Rebellious behaviour is often referred to as going against the norm and derives its value from breaking rules. Previous academic research (Gielen & Van Leeuwen, 2013), on the subject, has provided suggestions and techniques to design for this. However, there has been no clear or obvious conclusion as of yet, whether or how rebellious play can be promoted and supported through design.Therefore the brief for this graduation assignment was to “ re-think the bangerik & develop the Bangerik concept and investigate the occurrence of rebellious behaviour during play. As secondary goals; gain insights in designing and researching for rebellious play.”X-eo builds upon the bangerik concept developed during the compulsory DFI master‘s course Interactive Technology Design (ITD) during the 2013/2014 academic year at the faculty of IDE at the Delft University of Technology. Bangerik is an interactive free-flowing game that encourages children to be rebellious in a playful context. It consisted of a wearable worn on the wrist, where the goal of the game to raise their opponent‘s heart rate by scaring them and then steal their lives by tapping their wristband. The project is broken down into four distinct phases: Understand, Ideate, Make and Evaluate. Understand: The “understand“ phase was an immersion into the terminology behind the assignment through literature, an investigation of the original concept, online research of current rebellious concepts and potential technology that could be integrated into the final design to be tested at the end of the project. A definition of rebellious play was created and defined as “Where children can actively challenge what is in place and explore their behavioural boundaries, without having to face or endure any serious or lasting consequences“ This definition accompanied by a model of rebellious play was used to support the start of the ideate phase. The phase concluded with the establishment of research gaps to be investigated during the next stage of the project.Ideate: The “ideate“ phase consisted of 2 iterative design loops to find information that could not be obtained from traditional research methods such as literature reviews and interviews. Ideation focussed on the following research gaps, with prototypes created for each aspect and tested with children at a local school:How to play tag with Bangerik?How to attach something to the body?Where to place the tagging locations on the upper body?How to raise and lower heart rate during play and should this aspect remain in aspect?The video data from the testing sessions were analysed with the following conclusions established: The upper arms and chest are the most suitable tagging locations on the upper body. A garment is best to accommodate the tagging areas on the upper body. The heart rate aspect was a vital element and should be integrated into the final design. Feedback should be integrated into the final design to indicate when the players the heart rate is high and when they have lost a life. Make:The “make“ phase consisted of finalising the concept design and establishing aspects to be examined during the pilot study. Aesthetics, prototype behaviour and functions were finalised.From this point onwards the Bangerik concept evolved into the X-eo concept, a wearable garment tag game that offers the children the opportunities to steal lives from each other by raising other player’s heart rate. The tagging, heart rate and visual behaviour aspects of the concept were selected to be embodied into minimal viable prototypes for the pilot study. Evaluate: The “evaluate“ phase brought a close to the project with the prototypes being tested during the pilot study. The main focus for the pilot was whether the prototype provoked the occurrence of rebellious play behaviour and recommendations for design and research activities with the prototypes in the future. The following sub-questions were operationalised to determine conclusions to the overriding research questions:What strategies do the children implement during gameplay and are they rebellious?Do the children understand the visual feedback when their heart rate is high, when their lives are stolen, when they are out of the game and when their lives are reviving?A hierarchy of rules framework was created, so rebellious tendencies through the children‘s strategies could be identified and classified based on the rules they violated. In conclusion, rebellious behaviour was present during the testing session with all rules within the hierarchy framework being violated, with contextual and societal rules being the most popular. However it cannot be defined whether these behaviours were directly provoked due to the prototype, the context or the motivational state the children were in before completing the test. The hierarchy framework was a useful tool for classifying rebellious play behaviour. The report concludes with an evaluation of the research methodology applied, research & design recommendations and reflections with regards to conducting future research with the X-eo concept and on rebellious play behaviour.