There are a lot of hidden thing in this game. Hidden Item,Hidden Treasure Chest,Hidden Boss, Hidden Maps and other hidden things.
You can check one of the Hidden Treasure Chest in this video :
So don’t lose any chance of getting hidden things in this game, You need check all the spot in every map in this game, If you are lucky you will find some hidden spot and get new quest or item.
I will update daily in this sites whenever the game is start the open beta.