You can easily skip the broken level simply by just unlocking all levels and going to the next one.
Look at the "Starting Game / Unlocking Levels" Section of this guide below. If you want to do all the levels, or if that method doesn't work anymore, you'll have to follow the rest of this guide.

Good luck and try your best to not skip any other levels, as of now there are no other reported broken levels, but as far as I know the levels after 27 are untested.

Comment directly from SMG Studio on this guide:

May 5, 2025
SMG Studio
Good news! We've fixed this in the latest update!

However, they broke level 27 from reports I'm seeing so this guide may be required to progress through the game normally, and not just for getting the secrets achievement.

There is another comment on someone's review of the game saying that some of the new vault levels are also broken.. . here is the quote:

SMG Studio [developer] Posted: June 19 2025
We're looking at the levels now as yes Duoverse seems to be broken.

The review referencing this:
https://steamproxy.net/profiles/76561198393504105/recommended/471810/
Another review suggests reverting the game like this worked for them after the latest update:
https://steamproxy.net/profiles/76561198041497067/recommended/471810/

Past updates:
MAY 2025
Although I haven't tested it myself, the problem this guide describes should now be fixed. I did plan to test this myself at some point but I trust that it's been resolved now. I'm leaving this guide up as a reference just in case other problems come around, but likely you will not need to follow this guide anymore.
This guide was also featured on the Steamhunters website as a fix, so that's cool! Don't want to make a broken link there in case this helps someone else with a different game potentially.

OCTOBER 2023:
I just received this email yesterday (October 24th, 2023) from SMG Support:

We have just started development on some bug fixing on DeathSquared. While not fixed yet in around 2-4 months we should have this issue sorted for you.
​We will notify you once they are out!
​
​Regards,
Team@SMG

So hopefully this will not be an issue in a few months, but until then, this guide will still help you. I will update this guide when the game is updated, and will try to test it as well to see if it's actually fixed. So it's your choice if you want to wait for the update, or follow the guide. If you're impatient, read on!

NOTE ***As of October 2024 (1 year later) there is still no update to the game, so this remains the only way to get the achievements without cheating***

First of all, I want to say that I played through the entire game and got all the secrets in game before doing the steps in this guide. I looked through the Steam discussion pages, and even contacted the publisher about this issue. I could not contact the developer however because I have no way to contact them. The publishers just told me that they're aware of the issue and a fix is unlikely to happen because the developers have moved on to other projects and are hard to get a hold of.

Here is the email they sent me:

"Thanks for such a thorough description of this issue. Unfortunately, as you have found this has been an ongoing issue for a while now. At this moment the Secret Achievements cannot be unlocked due to a bug which we are yet to identify. The reason for this is that our developer team has moved on to new projects and it has become increasingly more difficult to investigate this issue without them. We do hope to fix this, and if you would like to be notified when such an update is made feel free to reply to this message and I will make a note to do so in the future."

It was discovered by someone on Steam that you can get this achievement by downgrading to an older version of the game, and it worked for me as well. I also discovered that this wasn't enough on it's own, just launching the game after already having found all the items will not work, nor will replaying a single level to get one of the items. I had to create a new install and get all the items again, by replaying the 10 levels with secret items, without the game thinking I had already done so.

All of this is a bit of a complicated process however so that's what this guide is about.

Guides used to create this one:
https://steamproxy.net/sharedfiles/filedetails/?id=1244721459
https://steamproxy.net/sharedfiles/filedetails/?id=1086279994

Here you have two options (you only need to do one):
You'll need to do this in the Steam Console, which you can access here with this address:
steam://open/console

Type this address into any web browser on your computer (like Google Chrome), and it should open the Steam client with the console open.

OR

You can also add "-console" into your Steam shortcut and quit and re-open Steam, but the above link is quicker.

In the Steam console at the bottom, type the following command depending on your version:
Windows 64-bit (most people will use this):
download_depot 471810 471813 5047273333078164064

Windows 32-bit:
download_depot 471810 471811 3193976426315929535

Mac:
download_depot 471810 471812 5549647531084071709

Linux:
download_depot 471810 471814 3945644673450910331 (There is only 1 Linux version however so the Linux version may not have this problem)

After you type the command wait for a bit (how long depends on your Internet speed), and you'll see this in the console:

The files you downloaded above are in your steamapps/content folder, you need to replace the installed files with these ones. Here's how that's done.

To find your installation folder:
Right click on Death Squared in your Steam Library and go to Properties:
Then click "Local Files" and "Browse"
Also you should make sure you disable Steam Cloud saving here:

Erase the contents of the folder that opens up:
Likely will be: C:\Program Files (x86)\Steam\steamapps\common\Death Squared

The files you downloaded earlier in the console will be downloaded to your default Steam Library folder in a folder named "content". For most users, it will be this folder:
C:\Program Files (x86)\Steam\steamapps\content\app_471810\depot_471813
Copy (or move) the contents of this folder into the "common\Death Squared" folder you found above when you hit the "Browse" button earlier.

Erase your save file (to reset the items found count):
Rename (or just delete entirely) the "Death Squared" folder here to something like "Death Squared2" in this folder:
C:\Users\<yourusernamehere>\AppData\LocalLow\SMG Studio
If you disabled Cloud saving above, then this folder will be re-created with a blank one when you start the game next.

Launch the Game in Steam normally, and go to level select screen:

When on this screen, do the following code on your Keyboard or Gamepad:
Up, Up, Down, Down, Right, Left, Right, Left, Down.
If you did it correctly you'll hear a sound and you'll be sent back to the main menu.
When you go back into the level select, all the levels will be unlocked!
Credit to this cheat goes to the SMG Studios Youtube channel, video here:
https://www.youtube.com/watch?v=PRfJqtCZIUc
Now you can play any level you want, such as level 27 to continue playing the game normally.
There are more levels added after the May 2025 update however that will not be playable until you undo the changes in this guide, by either reinstalling the game, or verifying integrity of the game files.
**Keep in mind though there are reports that other levels are also broken too!

This part is no longer the focus of the guide for the current version of the game, but just in case you want to know the secrets I've left them in here.

Once everything is all setup, the game is loaded, and you have a new savefile, replay the following levels:
12, 31, 35, 37, 46, 49, 62, 71, 74, 79.
You only need to grab the secret items, you don't have to actually complete the levels! Once you grab the secret items, you can exit the level and go to the next one.

Here are the video guides to complete and get each secret item:
NOTE: These are not my videos, all credit goes to the creator of the 100% guide listed in the Intro above

https://www.youtube.com/watch?v=D1o6CVhtBMU
https://www.youtube.com/watch?v=wuUaCuVCDec
https://www.youtube.com/watch?v=qyjWy_2toTo
https://www.youtube.com/watch?v=RnYu4ztI_ts
https://www.youtube.com/watch?v=EY-KMX4vpQs
https://www.youtube.com/watch?v=FyH5mToYnhk
https://www.youtube.com/watch?v=NoULSIdmNR0
https://www.youtube.com/watch?v=C1n9_abGMWU
https://www.youtube.com/watch?v=AzFu9tj_Q9I
https://www.youtube.com/watch?v=z9poXPcd2yw

Congrats! Feel free to leave a comment below if anything is incorrect, or if there are any spelling/grammar mishaps that should be fixed. Enjoy!