Der Tod ist vor uns, etwa wie im Schulzimmer an der Wand ein Bild der Alexanderschlacht. Es kommt darauf an, durch unsere Taten noch in diesem Leben das Bild zu verdunkeln oder gar auszulöschen.
Death is in front of us, rather as on the schoolroom wall there is a reproduction of Alexander's Battle. The thing is to darken, or even indeed to blot out, the picture in this one life of ours through our actions. [Kaiser/Wilkins]
Death is ahead of us, say in the way in our classrooms we had a picture of Alexander the Great in battle. What must be done is by our actions to blot out or obscure the picture, in our lifetimes. [Hofmann]
In the Kaiser/Wilkins edition, this aphorism is followed by another, much longer one, numbered 89, while, in the Hofmann translation, this aphorism is marked 88/89 and the longer aphorism is presented as number 104.
This one seems to say that we go through life with some ideal before us, and that our life's purpose is to efface that goal insofar as it is a matter of imitating some hero of the past, by achieving some accomplishment which is heroic in its own right, and so may stand on its own as a new painting on the wall for the generation that comes after.
The difficulty with that reading is that the image is not replaced by a new image but darkened and blotted out, which invokes the idea of forgetting more readily than it does the idea of memorializing.
Es kommt darauf an means something like, the thing that really matters is ... There is no "must" in the sense of a moral imperitive or practical necessity. The issue is what matters, and what matters is not the battle or the Alexandrian ideal, but taking action.