Here, Kinbote references an old board game in which players roll dice to move through a series of squares, trying to reach the end. Notably, there are some traps: if a player lands on a square with a skull on it, for instance, they lose. The implication here is that the story of Gradus and Shade (explored further in the note to line 209, which is presumably what’s meant by “square 209”) is essentially a board game whose stakes are death. The reference to toy tin airplanes seems to evoke Gradus, whom Kinbote insistently associates with air travel, and calling his Commentary a “wild-goose game” seems to be a play on the phrase “wild goose chase,” which means an impossible quest. This is fairly apt, since Kinbote’s Commentary is unrelated to Shade’s poem (so trying to understand the poem by reading his Commentary would be a goose chase) and, furthermore, his Commentary relays his delusions, so it’s not always possible to pin down the truth of what he’s saying.