Game Design Document for a Co-Op Survival Game

Develop a comprehensive game design document for a co-op survival game, focusing on a post-apocalyptic setting. The game should feature a dynamic weather system, day-night cycles, and a variety of enemies and resources. Include descriptions of the game's mechanics, levels, and objectives. Define the roles and responsibilities of each player in a co-op game session, including communication, resource management, and combat strategies. Provide a detailed breakdown of the game's systems, including crafting, building, and exploration. Include a list of key features, technical requirements, and a high-level design overview.