How to Find Ultra Secret Rooms

Repentance added a new type of secret rooms, which can only be found via certain items that are able to create red rooms. Most ultra secret rooms contain angel items, making them very rewarding to look for. This guide will teach you how to find them much more reliably.

Warning!

After more than a year of using this method, me and my friend have concluded that it is only about 80-90% reliable. As with regular and super secret rooms, sometimes the game doesn't care about rules and spawns ultra secret rooms regardless of special room proximity. Unfortunately, it's impossible to find out how exactly level generation works without the game's source code.

However, the strategy is still more reliable than whatever nonsense is written on the wiki at this moment (December 27, 2022), and it seems like ultra secret rooms do prefer spawning next to special rooms, even if such behavior is not guaranteed.

Prerequisites

In order to find an ultra secret room, you will need an item/consumable capable of creating red rooms. Obviously, the most reliable one the Red Key, but you can also use Cracked Key or Soul of Cain. The Crystal Key trinket opens red rooms too, but you can't control it so it won't be very helpful here.

Since red rooms cannot be created in greed mode, ultra secret rooms are limited to regular runs. Furthermore, due to the fact that secret rooms of all kinds don't exist in the Ascension sequence, you can't find them there either.

Generation Rules

Under normal circumstances, an ultra secret room will be generated between 2 (sometimes more) red rooms.

• At least one of these red rooms must be connected to any special room except boss rooms (treasure room, shop, arcade, regular or super secret room etc).
  
• Both of these red rooms must be connected to at least one non-red room (but it cannot be the same one if it's the only non-red room both red rooms border with)

The level usually has 3+ possible spots for an ultra secret room, but if there aren't any valid spots for these rules to apply, the second rule will be disregarded.

If the level generation works as intended, you will only need to create one red room to find the ultra secret room, as it is revealed immediately after you open the neighboring red room.

Here are some useful examples of valid and invalid locations of ultra secret rooms. Obviously, there are many more possibilities, but these are going to be the most common:

• Gray square = regular room
  
• Gray square with a star = special room
  
• Bright red square = red room near a special room
  
• Dark red square = red room near a regular room
  
• Question mark = possible ultra secret room location

Map Examination

Now that we know the rules abided by ultra secret rooms, we can start looking at the map of our floor. Having items/cards that reveal parts of the map will help immensely. If you don't have any, just rely on your gut until you've full cleared the floor. Make sure you have a good understanding of how to look for super secret rooms, since they often act as the final piece of the puzzle when it comes to our task. Don't collect any batteries you find until you've revealed the whole map.


First, printscreen your full map and paste it in paint.

Then, draw the possible neighboring red rooms for each of your special rooms (without looking at the rooms themselves, only look at the map!), besides the boss room. Place a white square in spots where a red room cannot be created.

Afterwards, do the same for regular rooms, but in a darker color to make it more distinct.

Now, apply the rules mentioned above. Look at the empty spots on your map with 2 or more red neighbors, at least one of which is bright red. Don't forget about the "it cannot be the same room if it's the only non-red room both red rooms border with" part of the second rule.
If the spot you're examining is in an invalid position, place a white square on it. If you find a possible spot for an ultra secret room, mark it.

That's it. Return to the game and use your item to open a red room which neighbors with one of the marked spots. If you have red rooms that have multiple marked spots near them, opening those ones should be your priority.

Keep in mind that sometimes you won't be able to open one of the red rooms leading to your marked spot. This does not mean that your spot is invalid, you will just need to find another way to get into the neighboring red room. In my example, I was forced to go through the curse room because I couldn't create a red room below it.

Other Examples

This is the map that I used for Sheol. Due to the bug I talked about in the "Warning!" section, it wasn't correct and the ultra secret room turned out to be adjacent to 2 red rooms, neither of which were touching a special room.

[ᴼDAE]

Breakfast with no hog still hasnt released this 'guide' they speak of. Thanks to @Danizk0 for your efforts. This guide of yours has been very helpful

[Squelchyman]

@the bee buzzer please make this guide sometime I am interested in how your method is 🥺. Also thanks Danizk0, this guide works a lotta the time :)

[wind me up]

yes cause i do have a more reliable way, or at least something to consider

[Danizk0]

Does that matter? If Ultra Secret Rooms tend to be connected to special rooms, then following the steps in this guide is still your best option (unless you discovered a more reliable way to look for them). I'm curious about what you found, so don't forget to tell us when the guide is finished.

[wind me up]

yall this is inaccurate: them appearing connected to special rooms is a correlation, but not causation. ill be making a guide that explains why they TEND to connect to special rooms.

in short, its not that ultra rooms appear connected to secret rooms, its that special rooms tend to appear where ultra rooms would connect.

[swiss_cheese88]

i dont think they are, but they could be. also, i barely get red key and go alt paths

[Danizk0]

Good question. I never treated them as such, but they might be.

[swiss_cheese88]

do mirror rooms count as special rooms?

[Avenging Angel]

I found a very interesting ultra-secret room. So the generation seems to sometimes do what it wants.
https://i.imgur.com/W6DGN8R.jpg

[Poop]

Makes sense, thank you!