Bipeds regularly encounter soft surfaces with changing properties when running in the natural world. However, most bipedal running experiments are conducted on treadmills or hard terrain. This study addresses the effects of soft terrain on unsteady overground bipedal running. Experiments were set up where guinea fowls ran down a hard-ground runway with a soft terrain patch in the middle to test our hypothesis that terrains of varying stiffness and damping properties will yield differing gait dynamics and neuromechanical control priorities in locomotion. Four different types of terrain were used: memory foam, stiff foam, sand, and level ground for a control. Preliminary results showed differences in the average vertical forces, fore-aft forces, and fore-aft impulses calculated for each terrain type. The most apparent difference was an extra peak in the average fore-aft force. K-means clustering showed groups of forces existed independent of terrain type and individual. Further analysis is being conducted to determine if the preliminary differences in clusters and force trajectories are related to terrain type.