A new guidance law is proposed for interceptor missiles by using a differential game formulation with bounded controls. The interceptor is steered by the aerodynamic-lift control system and the divert-thrusters control system. By using game space decomposition, the parameter effects of divert-thrusters control system on homing performance are investigated. Under propellant limits and given the time constant of the divert-thrusters control system, the hit-to-kill performance requires the following conditions. Firstly, the maximum acceleration generated by the divert-thrusters control system is greater than a critical value. Secondly, the thrusters close after interception terminates. Thirdly, the operation time of the divert-thrusters control system is sufficient long to cancel the miss distance. These results are also demonstrated by a realistic ballistic missile-defense simulation program.