Autism Spectrum Disorder is a neurodevelopment condition that significantly impacts social communication and interaction as well as behavior impairments, including restricted and repetitive patterns of behavior, interests, or activities. In recent years, numerous studies have proposed serious games as a way to aid in the therapy of children with ASD. Hence, it is crucial to evaluate the effectiveness of such games and obtain robust evidence of their positive influence on this type of treatment. In this study, we aim to explore the evaluation of games for autistic children by conducting a Systematic Literature Review. We analyze the methods utilized to evaluate these games, their application and combination, the quality aspects assessed, and the number and characteristics (e.g., age and special need) of the participants involved in the evaluation process. Furthermore, we present a compilation of the study findings for each evaluation method. Our findings reveal that there is no standardized methodology since different methods have been utilized and combined in various ways to evaluate serious games that support the treatment of ASD children. As contributions, this paper provides valuable insights into how serious games have been evaluated in this context and can be useful for researchers and game designers working in the field.