Situated inside a virtual world in the late 21st century, you play an unnamed hacker who infiltrates the AIDA network, an ex-military training simulator where you engage in combat against a gamma of alien bug-like creatures. This system, despite coming to a halt years ago, keeps on expanding itself due to the way it was built, and recently, has been getting attention for having hackers break into its deeper sectors in search of fame and profit by selling classified data found within the system. However, this is not the hacker's paradise, a rumor has it that those who dare invade go deep into the system can contract the "Achiba Syndrome", which keeps the user's mind trapped inside the simulation for eternity.