An Nb solid electrolytic capacitor is disclosed which comprises: an anode body made from an Nb-based material, the anode body having a nitrogen content of about 7,500 ppm to about 47,000 ppm; a dielectric layer formed over the surface of the anode body; a solid electrolyte layer formed on the dielectric layer; and a cathode body formed on the surface of the solid electrolyte layer. The play extension system is used by combination with the toy system in which a user can change the setting of parameters affecting motion control of a driving machine, for extending a playing method with the toy system. The patterned upper metal layer is disposed on and bonded to the electric insulating ceramic layer.