Citing Ray Bradbury as a primary influence, this feels very much like a SF short story from the 50s or 60s, the sort of SF you could make a movie about without any need for a special effects budget. The protagonist, a child, lives with his parents on an island across the bay from Astro City. Earth is at war with Mars, and the protagonist plays make-believe games based on this distant conflict. But then a rocket-man washes up on the shore, and reality and fantasy intermingle. (There is a general feeling of WW2 fiction here.)
Though capable overall, both the writing and the overall design have some rough patches. The prose feels a little first-draftish in places. Most of the gameplay is quite narrowly focused -- probably too much so, in the make-believe sequence -- but there are a couple of points where the solution is a little counterintuitive. The denouement is rather heavily foreshadowed, the protagonist is perhaps a little bit too much of a Disney innocent. But there are many gleaming moments here, little bursts of rich, world-grounded imagery that make this feel less like a fantastic piece and more like a childhood memoir.
As science fiction IF goes, it's uncommonly good in that it has its feet planted on the ground, it grasps and is concerned about the flight-of-fancy aspect of the genre.