In the year 2002 AD, incurable diseases and unseen raise in criminal activities have brought the human society onto the verge of collapse. By that time, genetic engineering became so highly developed that it was finally possible to produce cybernetic organisms functioning like humans for all purposes. However, since the authorities were hesitant in their treatment of the cyborgs, they began joining criminal organizations, which used them as formidable soldiers in their battles against the Establishment. Eventually, a mercenary organization known as Blade Warrior was hired to confront them. Sou, one of the youngest members of the team, is sent to deal with a gang of marauding cyborgs in the city's shady area, without realizing that this mission will be just the beginning of a dangerous journey.

Zyclunt is a side-scrolling action game. The player controls Sou as he advances through linear stages, fighting enemies in his way. Sou is armed with a sword and can jump and duck as well. The game has beat-em-up elements in that it only allows the player character to advance to the next segment of the area if all the enemies have been defeated. Ranged weapons come in limited quantities and must be picked up in the stages. Most of the enemies in the game are cyborgs, robots, and machines.