Until the Super Soaker came along in 1990, water guns hadn’t changed much in over a century. But the Super Soaker was 28 years ago, and a group of German engineers and designers think it’s finally time for water guns to evolve again. They’ve created the self-filling Spyra One that fires quick bursts of water instead of a steady stream, which promises to improve accuracy and distance. The Super Soaker was a staple of my childhood, as it was for millions of other kids, but most of my summer afternoons were either spent refilling the blaster, or endlessly pumping air...