You must ensure the DLC region matches your base game. If you have the North American version of Stretchmo, you need the USA DLC CIA; otherwise, the game won't recognize the extra levels.

Because the eShop is closed, new players can no longer buy the DLC officially. This has led many to look for archived CIA files.

Since sharing direct download links to copyrighted CIA files is often restricted on major platforms, the 3DS community relies on a few well-known archives:

Always ensure the base Stretchmo app is installed before installing the DLC CIA. Even though the base game was free, the DLC acts as a "key" to unlock the levels.

Finding specific "CIA" files for Nintendo 3DS games like can be a bit tricky because the official Nintendo eShop for the 3DS has been closed. Since Stretchmo is a "free-to-start" game, the actual puzzles and levels were sold as Downloadable Content (DLC), which are now difficult to acquire legitimately. What is Stretchmo?