Ever noticed that you don't get 100% completion when finishing a level, or that there is an achievement to find a secret room? Secret rooms are a hidden room found on each level (always exactly one per level) that contains an item, or uncommonly an enchantment room, or rarely a resource obelisk. They require bombing certain spots to open.

As well as 100% floor completion and a free item or other useful things, opening secret rooms can have other benefits as well, covered later in this guide!

Just to clear up terminology - adjacent rooms are the 1-4 rooms that surround any other room. Adjacent walls are the walls in these adjacent rooms that face the original room.

Secret rooms are opened by bombing adjacent walls to the secret room in the place a gate would normally spawn. The bomb has to be fairly close, but does have a good amount of leeway. This will open a special looking gate in all rooms adjacent to the secret room. Just walk though any of these gates to gain entry.

There are ways to find the location of secret rooms, some easier than others. When put together though, you should always be finding the secret room on each level!

The first thing to note is that secret rooms can only spawn in certain places. The rules are, as currently determined:

• Secret rooms are always have 3 or 4 adjacent rooms, EXCEPT when the only places it could spawn like this break the rules below. In these rare cases, secret rooms will only have 1 or 2 adjacent rooms.
  
• They can't spawn adjacent to certain rooms: Boss rooms, shops, enchantment rooms, and puzzle rooms.
  
• All adjacent rooms can lead into the secret room. Some rooms can't have gates on certain sides, normally because the environment blocks them - things like lakes or tree clusters. The potential gate can also be blocked by red pits. If any the adjacent walls can't spawn a gate to the potential secret room, then the secret room isn't there.

Now that you know where they can spawn, here is how you can find them:

• When a bomb is dropped in a room, if that room is adjacent to a secret room, a spot will appear on the adjacent wall that indicates that you can bomb there to gain access to the secret room. This spot is shimmering patch (like hot air) with bright lights floating around. Make sure to look for this patch whenever you have dropped a bomb in a room. See the image below to know what to look for.
  
  
• All adjacent rooms will have a place to open the secret room. Once the room is open, it will open itself for all adjacent rooms, without having to bomb the other places. Don't worry about having to be in a specific room, any adjacent room works.
  
• When bombing a red pile, if you think a secret room could be adjacent, try to position the bomb on the edge of the pile so the bomb is close to where the secret room gate could be. This has a chance to save you a bomb. Even if it doesn't open the secret room, it will reveal the shimmer if the secret room is adjacent.

If you haven't found the secret room naturally by dropping bombs, here is a step-by-step guide on how to find it (stop any any point if you do find it, of course)!

1. Note the possible spawning rooms on your map. See the list of rules to determine where it could have spawned. See the image at the end of this section for an idea of what this looks like.
   
2. Check ALL adjacent rooms to the possible spawn locations. Make sure these rooms follow the rules for secret room spawning. Make sure any bombs you might have dropped in these rooms didn't reveal the shimmer. To check if you have dropped a bomb in a room, look for a colourful circle on the ground - these are left behind by dropped bombs. Also, if there are any red piles in these rooms, make sure to bomb them (you should do this for all red piles anyway).
   
3. Now that you know where the room could have spawned, it's time to start bombing. Drop bombs on the adjacent wall to a possible secret room, to either reveal it, or show it isn't there. Also, here is a priority list (go for these rooms first to increase your chances, and if a room meets multiple priorities, do it first):
   
   1. Any potential spot with 4 surrounding rooms. In the event that this happens, you can usually find the room there.
      
   2. Any adjacent room that is adjacent to multiple potential spots. Pick a wall to bomb. Here, you will either open the gate, reveal the shimmer on the other wall, or reveal that neither of the potential spots has the room. This will save bombs and time.
      
   3. Any potential spots you feel lucky - if you haven't found it by this point, and you still have multiple possible locations, it's luck by this point.

Secret rooms have another function. While rooms that require bombs and/or keys to open normally only have the one closed-off entry point, if a secret room spawns adjacent to them, entry to the closed room via the secret room will not be blocked!

To take full advantage of this, when clearing a level, do every room that isn't the boss room or a blocked room. Then, if the secret room is yet to be found, follow the step-by-step guide from the previous section, but add these as the third and fourth priority for rooms to bomb:

• If the possible secret room would lead into a blocked room.
  
• If the room adjacent to the secret room has a bomb gate. Bomb the gate, and see if it reveals the shimmer.

If this guide helped you, don't forget to give it a thumbs up to increase its visibility to other players. Thank you for reading, and thank you to these people for their contributions!

• Jarlaxle: For helping me spot the pattern that rooms with marked exits (such as in shops and puzzle rooms) don't have secret rooms adjacent.
  
• The Gamaniac: For pointing out there are are cases where the 3 or 4 adjacent rooms rule doesn't apply.