WIN (applied psychology on teaching and technology War Interactive Negotiation) is a highly interactive serious game designed to be used either in educational settings or for on-the-job training for teams wishing to fill in their soft skills clusters gap enhancing creative thinking, problem-solving, negotiating under pressure, time-management skills, team building and leadership skills. The game design is human-focused that is, it works on players’ feelings, reasons, vested interests and insecurities to drive them through the game. WIN is also user-centric since content is user-generated and peer-reviewed based on robust pedagogic design and a Computer Supported Collaborative Learning (CSCL) script. A custom-made environment with thematic buildings and high interaction and display fidelity has been designed in a 3D Virtual World, Second Life (SL). The storyline is based on Thucydides’ recount of the Peloponnesian war, dating back to 5th century BC, ancient Greece. The underlying learning design relies upon mapping Toulmin’s argumentation model to De Bono’s 6 Thinking Hats creative method for problem-solving. Players are randomly assigned through a custom script to either the Athenian or the Miloan team to negotiate and defend their vested interests. Each team writes an argument which the other rebuts. Each team gets timely feedback for their argument development from the opposing team based on clear criteria set on a scoreboard. The scoring criteria are Toulmin’s constituent parts of a good argument (data, claim, warrant, backing, qualifier, rebuttal). The narrative is actually emergent since no one can predict the argument each team will develop. The gamers become a thinking community, collaborating in their teams to achieve a cohesive outcome. Besides enhancement of particular soft skills clusters, the research also revealed a significant correlation between development of the knowledge, skills, attitudes and values most pertinent to the global citizenship mindset and the virtual identities of the players assumed in the game (Athenians-Miloans). The added value of the dissertation is that 1) there has been no study thus far on virtual identity and competence development (knowledge, skills and attitudes) that mirrors on pro-social behaviour. The existing studies are restricted either to perception of self or change of attitudes, they do not address the whole competence cluster let alone the Global Citizenship Competence. 2) custom tools have been programmed for this serious game, transcending shortcomings of the Linden scripting language to turn Second Life into a collaborative write-and-share platform enabling multiple users to view/edit/write/ at the same time. This way, the exchange of notecards which is the norm in educational interventions in SL and constrains authentic collaboration since each notecard is seen only by one participant at a time, is avoided 3) experiential learning and a practical how-to guide are emphasized moving away from the usual show-and-tell delivery fashion of learning in SL.4) the robust pedagogic design of the WIN is based on its innovative, creative argumentation framework which has been presented as a paper in the Third International Conference on Innovative Computing Technology (INTECH 2013), sponsored by IEEE) 5) αn iterative, agile methodology has been adopted for the design and development methodology of the game. The features of WIN as presented herein, are the result of the third, polished, iterative development cycle of the game (not the final though) which has been playtested and fine-tuned with input from live players/learners……. As of October 2015, the code that has been written for the tools/features of WIN will be open source.