Cooperative skills—such as communication, teamwork, and conflict resolution—are essential in both educational and professional contexts. We present AfterDay Horizon, a two-player cooperative game designed to foster these skills through asymmetric, cross-platform gameplay. Players take on distinct but interdependent roles: the Caretaker (VR) executes survival missions in a post-apocalyptic environment, while the Leader (web) provides strategic support through interactive mini-games. Time-sensitive tasks and role-specific responsibilities promote communication, coordination, and replayability. Experimental results show improvements in survival time, mission success, and task efficiency across repeated playthroughs—indicating strengthened cooperation and joint planning. Participants also reported high satisfaction, suggesting strong engagement and a positive reception of the game’s design.