Can we intend and generate karma for something that we believe is impossible?

Can we intend and generate karma for something that we believe is impossible? Suppose I am playing a video game and imagine that I am killing actual people on a battlefield, but believe this is not the case. Do I generate the karma of killing? What if someone has hooked it up to an AI on a battlefield or I suspect that they have. Do I generate the karma of killing in either of those cases? This is similar to this question, but I really wanted a authoritative answer, especially of this version. I suspect that it can generate unwholesome attitudes for a while. Is that the same as generating bad karma?