If you built a 'ring world' with a radius of 100Km around Mars, spincalc suggest angular velocity of 0.002357 rpm (about 7 hrs for 1 rev) - how much would this reduce the Coriolis effect? What would be an acceptable reduction for human comfort and even lower for human perception? How big would the ring need to be to achieve these values? Would you still feel anything walking or jumping tangentially to the rotation or along the direction of rotation?