Tsunkatse was a popular spectator sport in the Delta Quadrant invented by the Norcadians. In Tsunkatse, two contestants battled in an arena wearing polaron disruptors on their hands and feet, which delivered a bioplasmic charge on contact with the opponent's two target sensors, located on the sternum and between the shoulder blades. The object was to attack the opponent's sensors while defending one's own. There were four types of Tsunkatse matches: blue, red, green, and yellow. The objectives of blue and red matches were to knock out and kill your opponent respectively. (The objectives of green and yellow matches were never stated.)
In the 2370s, the sport was controlled by Penk, who captured various humanoids and forced them to fight in Tsunkatse matches against their will. These took place aboard his ship, and were transmitted live via hologram to various arenas in the sector. These fighters included a Pendari male, a male Hirogen fighter, and Seven of Nine. (VOY: "Tsunkatse")
In the 25th century alternate timeline of Star Trek Online, Tsunkatse, or at least artifacts of it, seems to have spread as far as the Alpha and Beta Quadrants, as a sword-like melee weapon called a "Tsunkatse Falchion" is commonly available. Given that Tsunkatse, as first encountered in the Delta Quadrant did not involve the use of weapons, it is possible that the sport may have evolved since then.
Tsunkatse Gloves are also available for players to acquire in-game, built with a Polaron Disruptor energy pack which allows the gloves to deal additional Disruptor damage, and has the potential to knock enemy weapons offline temporarily and inflict Disruptor Burn.