Sound is well known for improving immersion in video games. In many games sound also serves as an important game mechanism; in stealth games, for example, sounds triggered by player actions may attract enemy agents, and sounds created by enemy agents give useful information on where to target or avoid combat. Modelling sound, however, is computationally complex, and thus sound propagation is often restricted to highly localized contexts, or based on trivial propagation models such as a fixed radius that ignores the impact of obstacles. In this work, we describe an efficient approach to propagating sound in a real-time 2D game level. We use a heuristic ray-based approach, adapted to include diffraction, reflection, and transmission. Our design allows for dynamic geometries, avoids sound discontinuities, and can be tuned in various ways to trade-off accuracy for computation cost.