From this article，I will save some of unity video tutorial or reference with game design.(Maybe not only website)
Notice!Most of these are in English.And of coz u need a ‘ladder’.
【Vedio】How to becom a gamedesigner:Portal (This video helps the man who is totally an ice breaker in game design,and introduce the category of game designers)
【Book】《Introduction to Game Design》 This book recommand by my friend who is now studying abroad major in game design.It’s useful but not suit for junior.When you have made some game demo and really have a realistic understanding and multipul perspectives about how to design a game. And,Support Genuine if you can.