It is the 22nd century. Earth is invaded by aliens, led by a gigantic robotic snake. To repel the attack, Earth's scientists construct the Replicart machine, a deadly robot snake. The player takes the role of the pilot of the Replicart .
Replicart is a single-player only game variant that combines elements of Snake. In each of the 300 stages, you have to collect a certain amount of a substance called 'Biteslime'. Once you fulfill your quota, you can enter the next stage through an exit that opens on the left side of the screen. Collecting biteslime increases the length of your snake. If the head of your snake hits a wall or an enemy, you lose a life. The game enhances the basic Snake formula by adding power-ups like a Time Stop, which freezes enemies, speed increase/decrease, or level warps.
The Famicom Disk System version has undergone changes. There are only 100 stages, and after each 10 stages, you have to face a boss, which must be shot down before continuing to the next set of stages.