That's correct. I originally didn't implement other diagonals than numpad since, honestly, I didn't even think of it. I've just updated a v1.12 with HJKL (the VI keys), which to me are incredibly unintuitive but won't necessarily be for others, and are certainly better than nothing.
I don't mind the cheating key being available if you find it - I don't advertise it (some people would rather not know, I'm sure) but it's one way to get to experience more of the difficult game. I trust people to police themselves :)