Easy Mode: Your foes cower and fall before your unstoppable onslaught,
yet final victory will leave you wanting more.
Normal Mode: Hordes of aliens vie to destroy you, but nerves of
steel and a quick trigger finger give you a solid chance to prevail.
Heroic Mode: Your enemies are numerous as they are ferocious;
their attacks are devastating. Survival is not guaranteed.
Legendary Mode: You face opponents who have never known defeat,
who laugh in alien tongues at your efforts to survive.
