Evaluating software with users implies challenging tasks where users' abilities are sometimes taken to the limit. This process might turn a very unpleasant experience to users susceptible to anxiety and stress, such as users with Down syndrome. By consequence the poor performance of unpleasant users generates unreal results. We propose a gamified approach for software testing, which allows maintaining user's motivation and engagement with the test's activities, reducing anxiety and stress, having by consequence more reliable results. The gamified approach can be applied on any kind of software testing involving users, since it works over how the activities are presented to participants, once they have been defined according with the test goal. Results of the application, over 10 users with Down syndrome, suggest that the gamified approach maintains the emotional state of users in a positive way even when they made errors, got confused, or were forced to change/stop an activity.