Computer-based learn-by-doing environments have been used to provide students supportive and authentic settings for challenge-based learning. This chapter describes the design tradeoffs involved in interactive learning environment design, deployment, and authoring. It presents a combination of design choices in INDIE, a software tool for authoring and delivering learn-by-doing environments. INDIE’s design balances the tradeoffs and leverages Web technologies to improve the accessibility and deployability of learning environments as well as feedback generation and authorability. It explores a vision of learning environments that are more accessible and usable to students, more supportive and customizable to instructors, and more authorable to software developers.