Abstract. Quantitative verification is an established automated technique that can ensure predictability and dependability of software systems which exhibit probabilistic behaviour. Since offline usage of quantitative verification is infeasible for large-scale complex systems that continuously adapt to the changing environment, quantitative runtime verification was proposed as an alternative. Using an illustrative case study of communicating, distributed probabilistic processes, we formulate the problem of quantitative steering, a runtime technique that involves system monitoring, prediction of future errors, and enforcement of system's behaviour away from the error states. We consider a communication-based variant of steering where enforcement is achieved by modifying the contents of communication channels. Our approach is based on stochastic games, where one player is the system and the other players assume the role of the controller, and hence steering reduces to finding a controller strategy that meets the given quantitative goal. We discuss the solution to the quantitative steering problem and its extensions inspired by complex real-world scenarios.