Simulations can be extremely successful in acquainting participants with a negotiation’s logic and process, especially in those political systems in which negotiations are prominent, such as the European Union (EU). After a brief introduction on the simulations in teaching the European integration, in this article we present, step-by-step, a simulation game on the adoption of a real piece of European legislation: the regulation that implemented the European Citizens’ Initiative, one of the main innovations of the Lisbon Treaty. Special attention is devoted to the different phases of a simulation design, from the choice of the topic, the choice and allocation of roles, the preparation of all the necessary documentation, to the debriefing and assessment phases. The article originates from a 4-year long study with undergraduate students from two Italian universities.