Guitar Hero World Tour (and its cousin, Rock Band) is a game that is right up Artie's alley. Seriously, if there was an alley filled with Artie-like stuff, it would be chock to the brim of painting easels, guitars, senseless little games like Katamari Damacy or games where you could pretend you were playing an instrument, and stands selling pancakes. Also it would be very well lit and not at all a creepy alley like most alleys are. In any case, being inherently musical, the sounds of someone rocking out to something like Guitar Hero is basically a magical summoning dance for one Arthur P. Maddicks.
To that end, not too far after Shelby starts in on the guitar, Artie peeks in around the threshold of the doorway, an exclamation point already manifested over his head in bright blue. The great big grin of epic, excited proportions follows a moment later, and then Artie scoots into view, skirting around behind Shelby as to keep from getting in the way while she plays her song. He watches the highway as she goes along, and when the song is done and the crowd is busy waving its hands in the air for Shelby's rocking out, Artie takes the opportunity to point at the drums and look very hopeful.
Artie, for the record, is very good at looking hopeful. A second later, the picture of himself playing the fake-drums appears over his head, for good measure, in case she didn't understand what it is he wants.