We (NY area, 1970s) called it "tag" (or freeze-tag or tunnel-tag or whatever variation) and called the safe area "base."
I never heard "King's-ex" until college. A roommate originally from Virginia Beach used it jokingly on occasion, but only as a way to "call" something, such as "shotgun" in the car, or a place on the couch or something. I just said "I call shotgun," etc.
CK

#21 -- tag/tiggy.
#20 -- I would "call shotgun" but in other situations I would say "I got dibs on the . . . " or "Dibs on the . . . " NY 1960s. When a friend of mine had his first child, he wanted me and another friend to be co-godfathers. Unfortunately the Catholic Church doesn't allow that. So we tossed a coin, with the loser getting dibs on the next child.
Wikipedia can be wildly erratic in its usefulness, but the article that Vinny linked is a fascinating compilation of all sorts of variations of tag/tiggy/whatever you call it.
I never heard of "shotgun" until I was long past childhood. We always used "dibs." "Dibs on the front seat."
No one seems to have dibs on word's origins. This article discusses the meaning & origin of dibs and the British equivalent of bags or bagsie. (I remember reading "Bags I" somewhere; it might even have been Lord Peter.) The OED says the first known use of dibs is 1932. He quotes the Opies (to get back to the OP and "barley.")<blockquote>Quote
<hr>"A child in Southern England who spots the one cookie left on the plate might exclaim Bags it' or Baggsy,' whereupon by the sacred code of children the prize is hers. Her London counterpart might say Squits.' Other words which seem to work as well include Barley,' Bollars,' Jigs' and, in Scotland, Chaps' or Chucks.'"<hr></blockquote>The British Library is asking for contributions on words children use when playing "it, tig, tag or tiggy. " Playground Language
