Super Mario 64

Princess Peach uses a letter to invite Mario to come to her castle for a cake she has baked for him. When he arrives, Mario discovers that Bowser has invaded the castle and imprisoned the princess and her servants within its walls using the power of the castle's 120 Power Stars. The Power Stars are hidden in the castle's paintings, which serve as portals to other worlds where Bowser's minions keep watch over the Stars. Mario explores the castle and enters these worlds, gaining access to more rooms as he recovers more Stars.

Mario unlocks three doors to different floors of the castle with keys obtained by defeating Bowser in hidden worlds. After getting at least 70 of the 120 Stars, Mario breaks the curse of the endless stairs that block the entrance to Bowser's final hiding place. After Mario defeats Bowser in the final battle, and Bowser escapes, swearing revenge, he obtains a special Power Star which gives him the Wing Cap, and he flies back to the castle's courtyard. Peach is released from the stained-glass window above the castle's entrance, and she rewards Mario by kissing him on the nose and baking the cake that she had promised him.

Once Mario earns all 120 stars, he is able to access the roof of the castle via a cannon on the castle grounds, where Yoshi awaits him. Yoshi congratulates Mario on securing all 120 stars and grants him 100 extra lives in order to continue playing the game.