Play it if: you want a game rich in atmosphere and abstraction.
Don't play it if: you prefer something more like a literal story or intellectual challenge.
This is a very striking first publication. I think most of us would give an arm and a leg to put out something this good on the first try, and Yoon Ha Lee is to be commended on the thought and imagination she's put into this work.
In the basic technical respects, it's not all that remarkable. A short-to-mid-length game which isn't very puzzle-dense. Not much is going on here that's particularly revolutionary to the medium.
What makes it special is the setting and atmosphere. Here, the work comes alive in the imagination, and not just in the vivid, spellbinding language of description.
The Moonlit Tower reminds me the most of Emily Short's Metamorphoses; although the latter is a more puzzle-heavy exercise, the general feel of the two works is rather similar. Yes, there's a distinctive Eastern aesthetic influence (Korean and Mongolian, apparently), but the more overt impression to me is a pervading sense of toying with abstractions.
In Metamorphoses, it's the essence of things: their shapes, their sizes, their substances. In The Moonlit Tower, it's more about symbols: masks, lanterns, seasons. A sense of symmetry pervades the piece, with asymmetry being a puzzle to solve. A porcelain half-mask. A feast of bones just barely out of place. A compass dividing the four seasons. A symphony with a missing player. These otherwise disparate elements congregate to give an inescapable feeling of some greater whole.
The "story" itself is limited mainly to flashback and suggestion. In a way, it's almost a nudge - a small device intended to clarify one or two things, to quietly lay the framework for the final sequence. It's a testament to this story's belief in letting the player's imagination blossom that you can experience a profound sense of completion upon finishing The Moonlit Tower, even if you feel you never really knew the protagonist.
It's difficult to really say much more about this work. It's a bona fide tone poem - almost a more intimate, intricate IF successor to Strauss's Also Sprach Zarathustra - and as such is something more to be experienced and reveled in than dissected. I strongly recommend it.