this is just for example
Fog of war + Capture anything
Thus rendering the variant impossible.
what do you even mean?
you can capture the white king as black still...

Well I played similar game. This isn´t the end, but you have two options. Take queen and the knight will capture your king and you will lose. Do anything else and the queen will capture your king.
I hope this idea doesn´t exists already. I think there should be version of fog of war where you can capture your own pieces. Why? Sometimes you are checkmated and you can´t do anything and lose the next turn. But if you could capture your own piece you could still continue playing.