Serious games are considered to provide powerful and attractive ways to acquire complex cognitive skills for education and training. But existing platforms for development of game-based e-learning often appear either not to be very user-friendly or too rigid or costly. This article addresses the design, development and evaluation of a generic platform for fast and flexible development and delivery of a wide variety of scenario-based games that enables complex cognitive skills acquisition. We present the requirements for the EMERGO platform and which common components it offers to cater for most of the needed functionalities within scenario-based games. We explain how users in various roles can use the platform to manage, develop, deliver and play a broad variety of scenario-based games. Evaluation data are presented to back up the claim that the platform indeed allows for faster, more user-friendly and less costly development and delivery of scenario-based games. Seven years after the platform has been launched, it until now has proven successful and still continues to evolve. We close off with some conclusions and needs for further development.