Game Boy Color is the second major portable video game console made by Nintendo. The console was a successor to the original Game Boy and shared many similarities with it. Game Boy Color was backward compatible with all original Game Boy titles. The main innovation in the system, compared to its predecessor was its color screen that could display up to 56 different colors. The control elements were the same as in original Game Boy: a D-pad, A, B, Select and Start buttons. The games developed specifically for Game Boy Color could not be played on Game Boy, while the Game Boy titles when played on Game Boy Color were colored using built-in color palettes. The player could choose from 12 different pallets. Additionally, certain Game Boy games had their specific pallets. The most successful exclusive games on the system were titles from Pokémon, The Legend of Zelda and Super Mario series with Pokémon Gold and Silver selling more than 23 million copies worldwide.