In Civ-BE vanilla, the Ultrasonic Fence made it impossible for aliens to come within 2 tiles of a city. In Rising Tide, the mechanics were changed to merely discourage aliens to come close.

But how exactly does that work?

I assumed that the discouragement effect only gets weaker if the aliens are angry, but in a recent game I treated them super friendly (not attacking a single time) and a Kraken still completely ignored the fence and destroyed all my improvements. I even had the +1 range quest reward.

Am I missing something or is the fence currently broken?

  • Did you notice if the kraken had any damage? I've noticed that sometimes aliens on whatever landmass I'm expanding on will be inexplicably damaged when I'm not attacking them and there's no other civilizations anywhere near my region of the planet. My unsourced theory currently is that the "discouragement" is damage over time if the aliens hang around inside the fence's range too long.
    – Ellesedil
    Oct 28, 2015 at 19:55
  • @Ellesedil I had a friendly siege worm wreck all my improvements and take no damage over a span of about a dozen turns.
    – Troyen
    Oct 29, 2015 at 9:30
  • @Ellesedil The Kraken did not take any damage over of span of some 30 turns. Then I "poked" it once with a city strike and it ran away, but came back immediately. This may or may not have been a coincidence. Oct 29, 2015 at 13:49
  • @SebastianNegraszus I often use city strikes to deter the giant aliens
    – Jimmery
    Nov 3, 2015 at 12:42

1 Answer 1


The latest patch ( contains the following change:

Ultrasonic Fence is a stronger deterrent to keeping aliens away.

So it seems that, yes, the fence was weaker than intended. Let's see if this patch fixes the issue...

  • 1
    it should be noted that the Ultrasonic fence, even once patched, is less effective against the giant aliens (kraken, worms & makura) than the normal aliens.
    – Jimmery
    Nov 3, 2015 at 12:41

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