Gamerunner is set in a futuristic world where humans have destroyed the environment through pollution and radiation. The atmosphere is thick with toxic chemicals, and extremely corrosive acid rain falls from the sky. It is not safe for humans to go outside without protective headgear, and those who do venture out risk being attacked and killed for their hoods. The story is set in the city of Undone, a grim place where feral gangs roam the streets and life is hard for all but the privileged employees of Crater. This powerful and ruthless global corporation created and runs the Maze, a virtual reality online game that has become the opium of the masses. Those who work for Crater lead a protected life inside the headquarters of the company... but only as long as they continue to be useful.
Rick is a gamerunner, one of the players in the vast virtual world of the Maze. He enjoys a life of luxury inside the Crater tower because his father, Daed, a skilled designer, has played a vital role in creating the Maze and in keeping it running. When Daed recruits Rick to "kill" another player who is getting close to finishing the game, Rick agrees. He enters an area called the Roots, finds his way past traps and monsters, and finally manages to defeat the other player. Rick is then overcome with curiosity as to what lies at the end of the game. Despite Daed’s strict warnings not to complete the game himself, Rick cannot resist. He walks through the portal and discovers the Endgame.
Rick is suddenly pulled out of the game and back into real life, where he finds that his world has changed terribly. Daed has fallen out of favour with Crater, and their privileged position within its protected walls are at risk. Daed had promised them a game with no end, a game that could not be beaten; but Rick has just beaten it. Daed protects Rick by giving Crater the identity of another player, and Rick sees firsthand just how ruthless and cruel the company can be. Daed now desperately tries to put himself back into Crater’s good graces, as Rick begins to feel a growing urge to escape the tower and find out what the outside world is like.
Daed goes to another designer, Perdita, and begs her to give him a programme called ‘Asterion’. He reveals that he is dying, but seems to think that Asterion will help him live forever. Perdita refuses, and a distraught and confused Rick steals the code from her. Perdita confronts Daed, but in the ensuing fight is pushed from the window to plummet to her death below. Rick cannot believe what happened, but Daed attempts to persuade him that it is for the best. He tells Rick that the two of them know too much about the Maze; they are basically prisoners of Crater and will never be permitted to leave. He gives Rick a new, modified version of the virtual reality tank, but warns him not to enter the actual game until he is instructed that it is safe.
Rick and Daed attend the launch party for the new version of the Maze, during which Rick gets a little drunk. He sees Daed slip away and decides to follow him. Daed plugs himself into one of the new tanks, but it malfunctions, and by the time Rick finds him he is dead. Rick ignores Daed’s warnings and plugs himself into the Maze, where he is greeted by an avatar that looks exactly like Daed. Daed explains that he is real, not a computer-generated character, and that he is now within the game itself. He tells Rick to leave, and logs him out before Rick can ask any more questions.
Rick cannot bear the thought of staying at Crater any longer. He comes up with a desperate plan to escape, and begins to trash his room, filling it with flammable objects and deliberately starting a fire. Rick hopes that Crater's hidden cameras will burn up before he escapes, giving the impression that he died in his room. However, he leaves it a little too long to leave his room, and is blown out of the building in the ensuing blast. He plummets towards the ground far below, but hits a fence on his way down and miraculously survives the fall. Badly scorched in the fire, his back is now marked by symmetrical burns, like wings. He is finally free.