I've always wanted this sort of thing, but given up on the idea quickly, thinking that time travel in a multiplayer game just doesn't make any sense and there's

I've always wanted this sort of thing, but given up on the idea quickly, thinking that time travel in a multiplayer game just doesn't make any sense and there's no sensible way to come up with a way to make the mechanic work. But it seems I was wrong. This is impressive and could open a whole new strategic dimension to RTS gameplay.