This isn't due to any sort of story or
practical explanation however, but always due to invisible barriers where a player's ship and attacks won't penetrate, even at close range.
Not exact matches
My father,
however, never accepted this
explanation, which he found too complicated: We sweep the sand for a much more
practical reason: we want to know who's come and gone during the night.
Some cat fanciers have a more
practical explanation,
however, and blame another cat.