Serious games and gamified interventions have become increasingly popular among researchers and therapists dealing with the autistic audience. The number of studies on technology for autism has multiplied, with the aim to foster independence and improve learning outcomes. Nevertheless, designing interventions for Autism Spectrum Disorder is challenging, due to the complex clinical conditions and the broad range of symptoms covered by the disturbance. Thus, this systematic review investigates the current status of gamification resources for autism, with a special interest in the gamification elements and the User Interface design. We describe the planning and the searching procedures and present the data extracted from 30 primary sources. The studies analyzed show a multitude of gamification elements and a plethora of methods and strategies to support decision-making and improve accessibility in the development of autism-specific software. It is concluded that the existence of methodological gaps related to the definition of the target audience and the conduction of testing may impose additional challenges to the development process, whilst the combination of gamification elements is generally positive.