In the educational context a serious game (JS) can improve learning through its motivational aspects. To ensure that a JS meets user expectations, it would be very useful to know what features or criteria are key when conceiving them. The objective of this work is to identify key criteria that must be considered by the JS design methodologies, which will affect the success in the development and use of JS in the educational context. Therefore, we carry out a qualitative and quantitative content analysis investigation to define the criteria, which are necessary and sufficient for the design of the JS. The content analysis includes the compilation of scientific literature related to games for people with non-standard cognitive skills. Next, we calculate the TF-IDF metric (term frequency and inverse document frequency) in the documents group and with a set of logical statements; We infer the criteria that are considered necessary and sufficient to design the JS for educational purposes.