Our exploratory research aims at suggesting design principles for educational software dedicated to people with high functioning autism. In order to explore the efficiency of educational games, we developed an experimental protocol to study the influence of the specific constraints of the learning areas (spatial planning versus dialogue understanding) as well as Human Computer Interface modalities. We designed computer games that were tested with 10 teenagers diagnosed with high functioning autism, during 13 sessions, at the rate of one session per week. Participants' skills were assessed before and after a training period. A group of 10 typical children matched on academic level also took part in the experiment. A software platform was developed to manage interface modalities and log users' actions. Moreover, we annotated video recordings of two sessions. Results underline the influence of the task and interface modalities on executive functions.