Video games are an integral part of popular culture. The video game industry faces challenges with the increase in players' numbers and application areas including serious games. The increase in the number of players includes disabled players. Therefore, serious games have to consider these audiences who may be affected by one or more temporary or ongoing disabilities. Universally accessible games (UA-Games) aim to create interfaces that can be accessed and manipulated by the largest number of players. Currently few serious games include accessibility features, while accessibility should be considered at the beginning of the serious game design. Then how can we help designers and developers to include accessible features in an existing serious game? To this end, game engines must be efficient but also scalable and modular. This paper studies the interest of the Entity-Component-System (ECS) software architecture to integrate accessibility features in an existing serious game. As a case study, we will take a serious game developed with ECS yet not accessible: E-LearningScape. We will present the accessible features that we have integrated into the serious game and discuss the pros and cons of this approach. This feedback shows us that ECS provides very useful design flexibility to integrate unanticipated interaction features into serious games.