A keyswitch uses a combination of springs connected in serial for providing a return force to a keycap of the keyswitch. When the keycap moves toward a base of the keyswitch beyond a transition position, one of the springs stops continuously deforming. It leads to an increment of the elastic coefficient of the combination of springs and an increment of the elastic stored energy by the combination of springs. Therefore, during a pressing on the keycap, the keycap can provide a light force feedback and then a heavy force feedback to a user. Further, the keyswitch can use a switch with a lateral motion, which can reduce influence of a resilient force produced by the switch on the up and down movement of the keycap. The keyswitch also can use an elastic piece disposed beside the keycap, which can provide a tactile feedback to the user.