Designing game-based assessments requires coordinating the work of people from communities with little overlap, such as subject matter experts, game designers, software engineers, assessment specialists, and psychometricians. This chapter discusses three things that game designers should know about assessment to help their work come together toward the common goal: (1) Assessment design is compatible with game design, because they build on the same principles of learning. (2) Assessment is not really about numbers; it is about the structure of reasoning. (3) The key constraints of assessment design and game design need to be addressed, even if in rudimentary form, from the very beginning of the design process. The assessment design framework called 'evidenced centered design” is introduced to complement game design principles, so that designers can address assessment criteria such as reliability and validity jointly with game criteria such as engagement and interactivity. The ideas are illustrated with examples from the Packet Tracer simulation environment and Aspire game that are used in the Cisco Networking Academies for learning and assessing computer network engineering.