During "Sonic Adventure" development, Sonic Team discovered that the relatively simple character designs did not suit a 3D environment. The art style was modernized to alter the characters' proportions and make them appeal to Western audiences. Since "Sonic Adventure", the series' cast has expanded. Notable characters include Big, a large cat who fishes for his pet frog; the E-100 Series of robots; Shadow, a brooding black hedgehog; Rouge, a treasure-hunting bat; Blaze, a cat from an alternate dimension; and Silver, a telekinetic hedgehog from the future. The Chao creatures function as digital pets and minor gameplay elements, and Wisp creatures function as power-ups. Flicky, the blue bird from Sega's 1984 arcade game, appears in several "Sonic" games, most notably "3D Blast".