I'm stuck at the last boss level and hoping I could get some advice from here. Not only the boss can see me even though I've turned on the invisible mode, it can still see me and can easily kill me with it's "driller" in a matter of seconds! Have I done something wrong here? I've only being using Unlimited Health, Energy, Tactical Synergy, Mega Ammo, No Reload, Accuracy and Inventory options. Is or are any of these options I should be turning off when fighting the last boss?