I have RS NOR latches recording buttons pressed in the correct order, using AND gates to determine if the button pressed was the correct button. I'm building a separate set of AND gates to determine when a button is pressed out of order, in which case a circuit is triggered to reset the state of all of the NOR latches.
It's all simple enough, in theory. It gets quite a bit more complicated, when you take into account the relatively limited space, how easily redstone wires like to link to one another, and how fickle repeaters are about where they get and deliver their power. Also, I caught a sudden and severe case of Incompetent, while building the reset circuit, so there's inverters being placed and removed left, right, and center. I'll be coming back to it tomorrow.