Chords for 10 Classic Riffs! Only One Finger Needed! Beatles, Metallica, Blink 182, Green Day, James Bay, (). Spark is the smartest and most interesting app to learn and enjoy playing guitar. Spark is an all-around app for beginners and advanced players to learn any song with chords or master new skills with hundreds of lessons and games in Spark.Spark Chords|10 Classic Riffs! Only One Finger Needed! Beatles, Metallica, Blink 182, Green Day, James Bay,