Goethe wrote: > Yah, that would be fine for the same practical effect, although it couldn't > wholly undo things - if the previous one changed a rule and then a later > one put it back, at the very least an amendment number would change. It > would be possible to go further and retroactively reset amendment numbers > etc., but that becomes so radical for no purpose it would track a lot of > against votes, I think.
Proposal Y saying "set the gamestate to what it would be if Proposal X had not taken effect" ought to work, assuming that they're in the same batch, Y has Power >= 3 (the usual standard for hand-wave-y "set the gamestate to what it would be" proposals), and X does not block Y.