Man darf niemanden betrügen, auch nicht die Welt um ihren Sieg.
One must not cheat anyone, not even the world of its victory. [Kaiser/Wilkins]
It is wrong to cheat, even if it is the world of its victory. [Hofmann]
This seems to be a clarification of the point Kafka wished to make in the previous aphorism; here the idea of struggling with the world is less conspicuous and dominating.
What would cheating be, and what's wrong with it? To me, it seems as if cheating, in this case, is falseness. On the one hand, this might be taken in a conventional sense to mean that one must not be selfish, but on the other hand, it might mean that presenting yourself falsely, playing yourself rather than being yourself, is wrong.
What is the victory of the world, and why do I assume -- previous aphorism notwithstanding -- that its victory is a victory over me? Is the court victorious when Josef K. is killed? Is the castle victorious to the extent that it keeps K. from entering it? Is the gatekeeper victorious when he shuts the door to the law? In The Trial, Josef K. is apparently in a contest with the court, but it isn't clear that the court in any way recognizes him as an opponant it wishes to destroy. The conflict seems to be largely Josef K.'s own invention, but not entirely. Even when he is killed, he seems to have compelled the court to take drastic measures by his own actions, and the executioners pass the knife back and forth over him apparently with the expectation that he will seize it and kill himself. It isn't all in Josef K's head -- he is arrested, the court is real, the executioners are real. Would he have been cheating if he had tried to conduct his case in the usual way, as a client or defendant? He does not cheat in his resistance to the court; it would be playing along that would have been cheating.
The court has to destroy a real person, not a phantom. If it didn't, it wouldn't be a court. To exist, the world needs victories, and therefore needs losers.