The main character, a ball of tar named Gish, is in search of his beloved Brea, who has been kidnapped by the villainous unknown assailant. His journey deep into the underworld drags the player into an increasingly challenging labyrinth of puzzle-filled levels. Gish is well equipped to manipulate his gelatinous body through dangerous levels filled with deadly spikes and twisted abominations as he solves mind-boggling puzzles and sloshes his way through hours of wild gameplay.

Using his jello-like body GISH is able to adapt to his surroundings, becoming sticky to climb walls, slick to slide through tight cracks and heavy to break through walls, bad guys, and the like. By expanding his body at a rapid rate Gish is able to quickly project himself into the air and attach to almost anything in his path.