<![CDATA[General Background: Guidance and counseling services play a fundamental role in supporting adolescent development, particularly in fostering logical choice-making and problem-solving abilities. Specific Background: Conventional lecture-based counseling methods frequently fail to address high school students' deficiencies in formulating alternatives, evaluating consequences, and executing structured decisions. Knowledge Gap: Despite the acknowledged importance of rational decision-making, there remains a scarcity of interactive, game-based guidance media that systematically operationalize theoretical decision frameworks for secondary students. Aims: This study aimed to describe the needs analysis, development process, and feasibility level of the Game Detective Decision media designed to train students' decision-making skills. Results: Employing the 4D development model, the needs analysis revealed that only 36.8% of students exhibited positive decision-making responses, highlighting critical gaps in alternative generation and evaluation. Integrating Herbert A. Simon’s rational decision-making theory, the developed game achieved high expert validation (media expert score reaching 83.33% and material expert score reaching 81.25%) alongside high practicality ratings from school counselors (92.5%) and students (91.5%). Novelty: The study introduces an investigative, board-game-based counseling medium that translates multi-stage rational decision theory into an experiential learning format for high school students. Implications: The findings demonstrate that structured game-based tools provide school counselors with participatory and scalable frameworks to optimize group and classical guidance services. Highlights Identifying Critical Deficits in Student Alternative Generation and Evaluation Integrating Simon’s Rational Framework into Investigative Board Game Components Demonstrating High Expert-Validated Feasibility and Counselor Practicality Ratings Keywords Detective Decision Game; Decision-Making Skills; Guidance and Counseling; Rational Theory; Educational Game]]>
