: Often suggests a Nintendo DS ROM image, though ISO files are typically used for disc-based media (like PSP or Wii). The mismatch in file extension (ISO vs. NDS) is a common trope used to signal that the file is "wrong" or corrupted.
If you have encountered a download link for a file named "ds-amokrunner.iso" on a forum or deep-web mirror: ds-amokrunner.iso
: If you must investigate, always use a Virtual Machine (VM) and never mount the ISO on your primary operating system. : Often suggests a Nintendo DS ROM image,