Jokk'tai ("Sharpen Mind") is a Protoss game and mental exercise.
From ages of 70 years and up, young Protoss would practice focusing their psionic energies into various different geometric shapes and colors (Star Trek - Deep Space 9: Altonian brain teaser; Star Wars: Push-feather; Justice League: Hearts and Minds). These constructs of psionic energies would then be used in mock combat or problem solving tasks given by a teacher. The goal of most combat matches was to break an opponent's concentration without losing their own.
One of the points of this practice is to hone young minds so they can control their psionic abilities in more constructive manners. The most well known applications of these teachings is the formation and use of Psionic blades.