If risks are not identified, they are unlikely to be addressed, possibly resulting in undesirable consequences, such as fatal accidents or even loss of human lives. Furthermore, risks should be considered not only in terms of system behavior but also events occurring in the system environment -i.e., in a collaborative setting in which the system and its environment work together towards certain goals the system is intended to help achieve. In this paper, we present a goal-oriented risk analysis framework, Murphy+G, in which non-functional requirements (hereafter, NFRs) are treated as softgoals to be achieved and systematically addressed in terms of both the system and its environment during requirements engineering, by adopting what is called the Reference Model. A study of a smartphone app, Theia, which is intended to help blind people navigate indoors, is used for the purpose of both illustration and experimentation. In this study, NFRs (e.g., safety, reliability, timeliness, etc.) are treated as softgoals, and risks (e.g., fall down, injury, etc.) are identified, along with risk-mitigation strategies for both the system and its environment, with the help of an activity-oriented ontology. To see both the strengths and weaknesses of Murphy+G, a systematic methodology for risk analysis for collaborative systems, a controlled experiment has been carried out, in terms of three different versions of Theia implementations. Feedback from students show improvements on the accuracy of the risk analysis and the risk mitigation strategies devised, as well as enhanced users' experience with respect to increased confidence in navigating indoors, in a safe, timely, and reliable manner.