Cool idea for a puzzle. Way too hard for me, though...
Also a little tip: Be mindful of different keyboard layouts. On my layout (I'm from Germany) the Z and Y keys are swapped, so the Z key is not in the 3x3 layout, where it's supposed to be. Not a huge problem but a bit annoying.
It's worse for french players as this is what the relevant section looks like on their keyboards:
