The Nemesis Challenge is an unlockable challenge on Cave Story+ and the Nintendo 3DS eShop version. It can be unlocked by completing the game with the Nemesis in the player's possession. The player starts with a level 1 Nemesis, 10 HP and the Booster v0.8. The challenge takes place in three main areas, the Underside, the Leeward Side, and the Vents. All three use the same background as the Outer Wall. The songs that plays here are Pulse (in the starting area) and Geothermal. Enemies such as Fuzz, Fuzz Cores, Hoppy , Buyobuyo Bases , Buyobuyos , Sandcrocs, Fire Whirls, Night Ghosts, Bats and Orangebells are encountered, along with numerous paths with spikes. The Booster v2.0 is obtained near the entrance to the second area.
