...when you have flashbacks of your best killstreaks in Modern Warfare 2 (last night was my recent 33 killstreak, no nuke unfortunately) at the worst times (shouldnt elaborate further)
...when you have very serious and long deliberations about whether to play KOTOR 2, Morrowind, or Fallout 2
...when you start to wish trees could talk like Harold (FO1,2,3)