This document discusses the key elements that define games and engage players. It identifies that all games require players, objectives, procedures/rules, resources, and outcomes/boundaries. These formal elements work together in a system to create challenges and allow for play within a structured experience. Engaging players comes through balancing challenges, allowing for fantasy and imagination within the rules, and leveraging premises, characters, and stories to create emotional investment in the game. Ultimately, games are complex systems where the whole experience is greater than the sum of its individual parts.