One show was all it took for God’s Green Ghost to build itself a fan base. The improvisational group was formed when bandleader Ross Hamlin decided his old friend Chris McIntyre was long overdue for a visit. McIntyre and Hamlin went to high school together but, through McIntyre’s Brooklyn music connections, he also got to know Santa Fe-based musician Chris Jonas. “The natural inclination was that we should do something other than jam in the basement,” Hamlin says. So he, Jonas and McIntyre started writing music and put together an ensemble that includes JA Deane, Milton Villarrubia III and Katie Harlow. The April 16 show at the GiG Performance Space on Second Street, which saw a great crowd for a Wednesday night, solidified GGG as a collective that Santa Fe wants to see again. But keeping with its improvisational ideas, Hamlin says the group will include different musicians each time; visiting guests, who he also hopes will teach workshops while they visit; and a lineup that is determined by what sounds that guest artist needs.