spider legs

In the book spiderella at the end of the book. there is a game called spider legs. you try to make it a complete spider.I do not get the game. it says if your get any number on the dice besides six so 12345. If you roll a 2 and roll it again what will happen will  you loose legs or stay the same. It was a lot of information on the book I did not want to write every thing but I still do not know why it said that.