The paper explores a novel mechanism for flocking in self-propelled Janus colloids, where particles exhibit stronger repulsion on the front than on the rear. Unlike traditional flocking models that rely on alignment interactions, this study demonstrates that flocking can emerge through interactions that turn particles away from each other. The authors combine simulations, kinetic theory, and experiments to show that the polar state is stable due to particles achieving a balance between turning away from left and right neighbors. This mechanism requires particle repulsion, which, at high concentrations, produces active Wigner crystals. The findings bridge the gap between alignment-based and repulsion-based active matter, providing a robust framework for understanding flocking phenomena. The results also suggest that flocking can occur in cell collectives despite contact inhibition of locomotion, offering insights into the collective behavior of biological systems.The paper explores a novel mechanism for flocking in self-propelled Janus colloids, where particles exhibit stronger repulsion on the front than on the rear. Unlike traditional flocking models that rely on alignment interactions, this study demonstrates that flocking can emerge through interactions that turn particles away from each other. The authors combine simulations, kinetic theory, and experiments to show that the polar state is stable due to particles achieving a balance between turning away from left and right neighbors. This mechanism requires particle repulsion, which, at high concentrations, produces active Wigner crystals. The findings bridge the gap between alignment-based and repulsion-based active matter, providing a robust framework for understanding flocking phenomena. The results also suggest that flocking can occur in cell collectives despite contact inhibition of locomotion, offering insights into the collective behavior of biological systems.