Sneak In Destroy -v1.0- -ankoku Marimokan- ((new)) Link

If you manage to complete a mission without killing any human enemies (only destroying the Marimo reactors), you unlock "Ankoku Mode" for the next mission. In this mode, your character’s silhouette becomes pitch black, footsteps are silent even when running, but you cannot use firearms. It turns the game from Sneak In Destroy into Sneak In Sabotage – a pure phantom run.