Subreddits like r/3dspiracy have extensive megathreads and guides on how to safely find and install DLC for games that are no longer available for purchase. Safety and Requirements
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. Stretchmo 3DS (USA) DLC CIA
Many users have uploaded "Ghostlight" or eShop "Redump" collections to the Internet Archive. Searching for "3DS DLC CIA Collection" often yields results for the entire library. Many users have uploaded "Ghostlight" or eShop "Redump"
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. If you have the North American version of
Stretchmo (known as Fullblox in Europe) is the fourth game in the popular Pushmo puzzle series developed by Intelligent Systems. Unlike its predecessors, Stretchmo was released as a free download on the Nintendo eShop, giving players a set of introductory puzzles for free. To play the full game, users had to purchase "Attractions" (DLC packs) through an in-game menu. The DLC "CIA" Situation
Because the eShop is closed, new players can no longer buy the DLC officially. This has led many to look for archived CIA files.