Originally, control mechanisms were proposed to replace the need for human intervention in operational environments, and thus, enhance the precision and reaction time. Nowadays, new requirements in computer systems such as adaptation have made the design of control mechanisms more challenging. The Observer/Controller pattern is one of the control mechanisms proposed to control many interacting independent elements by making intelligent decisions. An important challenge in designing these mechanisms is that the knowledge needed for decision making is provided by experts; therefore, the process becomes time consuming and costly, depending on the availability of experts and their costs. In this paper, we hypothesize that employing a Game With A Purpose can help to improve the process of providing knowledge in such control mechanisms by using crowd-sourcing and involving non-expert humans in an enjoyable manner. This hypothesis has been investigated by Macro-phage+, a Game With A Purpose implemented for this goal. We conducted experiments evaluating Macrophage+, focusing on both its applicability and effectiveness in the context of the observer/controller pattern as well as its enjoyability for the players. The results show that Macrophage+ is a successful Game With A Purpose that involves non-expert humans in the application of the observer/controller pattern.