_Hydacorn_ is a timed puzzle-board game. The screen is divided into three
windows. First one is a working window, the second one shows a pattern that
must be arranged in the window next to it before time runs out, the third one
explains blocks change sequence. Using fire the player may change the block
accordance with the indicated order. Change can’t be reversed. The block may
be changed by placing the black box next to it. Each block covered by a black
box moves to the arrival place of the black box.