 The Thousand @-@ Year Door borrows many gameplay elements from its predecessor , such as a paper @-@ themed universe and a turn @-@ based battle system with an emphasis on action . For the majority of the game the player controls Mario , although Bowser and Princess Peach are playable at certain points . The plot follows Mario 's quest as he tries to retrieve the seven Crystal Stars and rescue Peach from the X @-@ Nauts . 
