The need for training surgeons for robotic surgeries is increasing with the increase in number of laparoscopic procedures performed with robots. The commercial simulators available are expensive and hence not available to all. This paper provides a method to develop a virtual reality based simulator with open source software and a game engine. Another feature included in the simulator is the use of patient-specific organ models. This is advantageous since it is safe and less expensive compared to other simulators, and also is more flexible due to the use of game engine. For a realistic simulation, a model of tool-tissue interaction is carried out between the tool and an external tumour using the method described. The reconstructed geometric organ model, after being meshed, is integrated into the laparoscopic surgical simulation system consisting of a haptic interface device and a graphic display. © 2015 ACM.