Elusive means difficult to understand, identify or define, and play, as we will see, clerly fits that bill.  Chapelle (1993) gives us greater insight into play’s allusive nature:

The word allusion is itself derived from the word ludere (to play).  Hence metaphor, operating as it does on the basis of allusion to identity where none necessarily exists, contains as its active ingredient the element of playfulness. The Oxford English Dictionary lists the following meanings.  Allude means “to play with, joke or jest at, dally with, touch lightly upon a subject; . . . to . . . make a game of, mock; . . . to play upon words, to refer by play of words; . . . to refer by the play of fancy; . . . to have an oblique, covert or indirect reference, to point as it were in passing; . . . to make an indirect or passing reference, to glance at, refer indirectly to; . . . to refer (a thing) as applicable, appropriate or belonging to; . . . to throw out by the way, to hint, suggest.”   Alluding means suggesting a likeness to.  Allusion means a symbolic reference or likening: a metaphor, parable, allegory.  Allusion means symbolic, metaphoric, figurative.

The essential element in metaphoric allusion is playfulness.  The object of playfulness is the reference to something that is not immediately at hand in what is visible.  It is no surprise that Freud would learn much about the compulsion to repeat from the Fort-Da game.  No only is the Fort-Da game, like all children’s play, a game of playful pretense and of allusion to a depth dimension that is not immediately manifest, it is also a game that captures the essence of all children’s play—and the essence of the compulsion to repeat.  That essence, which finds an archetypal image in the figure of Don Quixote, consists in the human fate of having to live in a world of psychological-cultural meaning. (pp. 124-125)