The game is released in 3dsx and Cia formats. The code is closed source and copyright of Retroguru (www.retroguru.com)
Release link (final) : http://www.retroguru.com/sqrxz3/sqrxz3-v.latest-nintendo3ds.zip
Check the Sqrz3 page http://www.sqrxz.de/sqrxz-3 for other platforms ports of this game.
First release - 3dsx and CIA (02 june 2017)
In the zip there are the Cia file and a folder with the 3dsx and the smdh files inside, to be used with a homebrew launcher. All the resources are included in the executable using romfs.
The game creates a sqrxz3 subfolder inside the 3ds folder if doesn't exist.