In my neighborhood in Philly, we called the game “Killers”, but it appears to be the same game as described by the NY kids as Skullie or Skillies. I have great memories of rigging-up a magnet on a string and fishing bottle caps out of the soda machine at the Flying A station on the corner of 5th and Sommerville. An entire side industry developed around collecting the caps. Not that we didn’t take the game seriously. We eventually painted the squares on the street; it was a dead-end so traffic was limited to occasional trucks going to and from the factory across the street.