This achievement can be obtained either online or offline in one of the survival modes. It is easiest if played with 4 players. Recommendations are to create Supaweapons as frequently as possible and use them sparingly to clear the screen. Save your nukes for last-ditch efforts. If only one person is alive there is often so much chaos that they are unaware all of their teammates are on respawn, so if you aren't the last person alive make certain to yell at that person to use a nuke and keep the game going! As soon as the indicated time is met, the achievement unlocks.