Gold and Red Rooms
There are four Gold Rooms and two Red Rooms. Each Chapter has 1 Gold Room, and Chapters 1 and 3 each have a Red Room.
Gold Room – The Gold Room is fairly easy to find, but it requires having beaten the game first. It is in the Abandoned Prison, very close to the first save point in the game. From the save point, just follow the tunnels until you can take a right, and the Gold Room will be right there. It contains a Forbidden Fruit which will be mandatory for entering the other Gold and Red Rooms.
Red Room – This room requires the Succubus and Soul Vision to access. In the Maze of Madness, at the far left corner is a massive underwater tunnel. The Succubus is the only one who can swim through it, so you will need to be using her to enter it. Once you enter the entrance room, you must use Soul Vision so that the door will open for you.
Gold Room – This room is found in the area where you need to chase after the Onoskelis so that you can possess her. Its located in the room that you burn down with a torch. At the back of the room is a small tunnel that you need to crawl through. Like other Gold Rooms, you need to use Soul Vision to open the door. You can very easily access this location by using the Succubus and traveling through the Succubus Area in the Hills of Agony, which leads you directly to this part of the chapter.
Gold Room – This room is rather tricky. It’s well hidden and in a very dark area. Go to the second big section of the Fallen Kingdom. As you exit the stone building, look to the right across the ceiling in the distance; you may notice a number of upside-down buildings, one of which has a functional window. Possess an Ifrit, and fly into that room. You’ll want to re-enter Soul Form as soon as you are inside so that you can possess one of the Martyrs who are here.
On the upper left side of the room, there is a doorway that you can only open when you use Soul Vision. It’s a little difficult to get to it, and it’s very dark. Once you are inside, it may be impossible to exit again. The door and its functionality seem to be somewhat bugged, and it doesn’t seem possible to leave through the door, at least not easily. You can grab everything inside, and then save and quit, and it should all count in your collection.
Red Room – While not required, this is the easiest to do with the Succubus. Take the Succubus to the big outdoor area near the beginning of the chapter, and hug the left sidewall. Eventually, you will go down a slope into a room with an Onoskelis and a table. A bit behind the table, there is a wall that will vanish when you use Soul Vision. Go inside here, and eventually, you will find a painting that will when inspected, changes a room elsewhere on the map.
Said room is found in the room with the giant crushing rock walls. This room is most easily found by following the Succubus area near the beginning of the stage, but an alternative method of accessing it is to go to the room with the Corpseball enemies rolling around on the ice. On the left side of that room is a small crevice that you can slip through. Once you are in the room, avoid the crushing rock walls, and you will find a door that is now open. This is the Red Room.
Gold Room – Probably the easiest Gold Room in the game to find, its near the save point/spawn point for the Floating Temple. Facing the save point, there is a doorway to the immediate left the save point. Go through this door, and continue through the next door beyond it, and follow the path around the back. Jump over the poison liquid, and the Golden Door should be plainly visible. As usual, you must use Soul Vision to enter.