答案:Casual games are distinguished by low barriers-to-entry. They require only a small amount of time per session, are easy to learn, and are readily available online. In contrast, a core game requires a much larger time investment. Core games typically require extended lengths of time per gameplay session (90 minutes to several hours), are highly immersive, and demand advanced skills for ongoing play. They may be available online, or may have specific hardware and software requirements. Hardcore gamers value realism in the game's contextual clues and challenge in the game's activities; casual gamers value ease of use and immediate gratification.