Social communication and interaction difficulties are characteristic of Autism Spectrum Disorder (ASD). Specifically, individuals with ASD often have difficulty initiating and maintaining conversations and understanding social norms and expectations. Previous studies have shown that serious games (SGs) can enhance cognitive, communicative, motor, and social skills in individuals with ASD. Integrating virtual agents (VAs) into SGs allows for targeted social skills training, providing personalized learning that considers user needs. Furthermore, Virtual Reality (VR) technology offers an immersive experience, making learning more engaging and agent interaction as realistic as possible through shared virtual social spaces. The current work aims to present a VR escape room-based SG designed to promote cooperative and social behaviors in adolescents with ASD. Specifically, the game requires the collaboration with a VA to solve a series of different puzzles and riddles. The project was developed through a co-design process involving various experts and professionals. A first prototype was developed, and a test is planned with participants with ASD to evaluate the usability and effectiveness of the SG.