Virtual Reality and Video games are becoming a part of everyday life and culture. In addition to their entertainment value, modern computer games are provided with Game Level Editors (GLE) which allow the user to create customized Virtual Environments (VE). Although they are inexpensive, GLE’s graphic, animation and realistic features can match professional software and allow the user to be immersed into a 3D environment. In a therapeutic framework, GLE’s VEs combined with virtual reality have been used in many fields including psychotherapy and more particularly exposure therapy, a procedure which aims to reduce phobic anxiety through confrontation with the feared situation. However, GLEs differ from each other in the possibilities of navigation, the number of options for creation, the power of the engine, and the flexibility of the Artificial Intelligence. In the present study, criteria for selecting the most relevant GLE for the construction of VEs related to Virtual Reality Exposure Based Therapy for one particular anxiety disorder, agoraphobia, are outlined. For agoraphobia, namely the fear of being in places where escape might be impossible or embarrassing, features the most various avoided situations among all phobias, it was selected to determine VEs requirements and to investigate different commercially available GLEs. Based on these criteria, the selected GLE Sandbox 2 (Crytek GmbH) was utilized to construct 9 distinct virtual situations in which samples of 18 agoraphobics were immersed. Within each VE, the participants contended with their least feared situation and their most feared one. Self report questionnaires as well as measures of heart rate and heart rate variability demonstrated increased fear levels within the feared virtual environments. Reported level of presence also indicated a patent involvement in the VEs and a clear immersive effect. There was a significant correlation between presence and anxiety. These data indicate that GLE’s artificial worlds combined with VR offers a viable possibility to establish a therapeutic environment at an affordable cost.