Underworld Raiders is a single player subgame in Kid Icarus: Defender of Light, similar to Face Raiders, where you shoot Underworld enemies from a first person view, moving the system to aim.
In each level, there is no dialogue, since the levels don't relate to the story. Pit will walk on his own through the level, but will often stop when enemies apear. The player must then aim and shoot the enemies with their weapon of choice, firing with the L button as always, but only able to fire standing charge shots of that weapon. Enemies will fire back at Pit, so the player has to 'dash' to dodge out of the way. To perform a dash, the player must quickly move the system in the direction the want to move, either left or right, but not very far to avoid dropping and damaging the system. If the player wishes to, they can even move themselves, taking quick steps to dash and dodge. After dodging, Pit will walk back to his original spot. Upon defeating a wave of enemies, Pit will continue walking along the level, often fighting enemies while walking. At the end of the level, you must fight a Boss to complete the level, often involving the player to move around much more. Some levels are in the air, so the player must 'dash' up and down rather than forward and backward. Power attacks are also available with the touch screen and control pad.
To prevent damage to the system, high intensities are not available, only 3.0 and 6.0 called Easy and Hard.
Play through relatively short levels based on Kid Icarus: Uprising, but with different enemy combinations and often with shortcuts to shorten the level, or more waves of enemies in patters to lengthen them.
1. Play through Chapter 1 of Kid Icarus: Uprising, fighting enemies at That First Town, with Twinbellows as a boss.
2. Fly quickly over the mountainous terrain and underground, get to Dark Lord Gaol's Castle, make your way through the castle and get to Dark Lord Gaol as a boss.
3. Soar through the skies in an Air Battle, fighting Underworld Enemies in the clouds with the Three Headed Hewdraw as a boss.
4. Fight through the Reaper Fortress, dodging out of sight from reapers, with the Great Reaper as a boss.
5. Fly through Pandora's Labarynth of Deciet, fighting enemies and eventually reach the end to face off with Pandora in a Land Battle.
6. Battle Underworld enemies as well as Dark Pit in ancient Ruins, with Dark Pit as a boss.
7. Fly over the desert and into the sea, shooting more foes. Reach the seafloor palace for a quick land battle and face off with Thanatos.
8. Battle through the Space Pirate Ship, fighting Space Pirates and Underworld Forces, with the Space Kraken as a boss, very similar to Chapter 8 of Uprising.
9. Battle against Medusa as a final battle! Using the Three Sacred Treasures is an available option.
Bonus Level: Defend Skyworld from many waves of enemies on a single floating island with the Shadow Phoenix as a boss.