Giant, humanoid mecha called Dennin (電忍, meaning "electric ninja") have mysteriously appeared in 16th century feudal Japan, radically changing the nature of warfare.
Kagerou is the sole surviving member of the White Fang, the robot ninja army of Oda Nobunaga, a daimyo known as the "Demon King." He takes control of the Aleste, an eight-metre tall, steam-powered mech, and uses it to defeat Nobunaga and the other warring feudal lords.
The game is a vertically scrolling shooter similar to M.U.S.H.A. The player controls a flying robot, which moves in any direction with the D-Pad. The player can change its movement speed (between eight different levels) with . Its main weapon is firing a stream of kunai. This weapon is initially a single stream but can be upgraded up to four streams by collecting Power Chips (and then those streams can be further upgraded, two at a time, to change the throwing knives into fireballs). The Aleste can also acquire a secondary weapon by collecting items. Picking up an item for the currently equipped special weapon upgrades the weapon, up to four levels (from 0 to 3). Picking up an item for a different special weapon changes to that weapon but keeps the same weapon level. Both weapons have rapid-fire and unlimited ammunition. The Aleste fires its main weapon alone with and its main weapon and secondary weapon simultaneously with .
The robot comes with two fixed options in front of it at all times, which can never be destroyed. The options absorb enemy bullets and damage enemies on contact. Secondary weapons are fired from these options. The options can be launched at enemies by holding for a moment to charge them and then releasing the button.
The Aleste is destroyed if hit by an enemy, which also downgrades its main weapon by one level. If the Aleste is hit while possessing a special weapon, it drops it as an item that can be collected again. The game ends if the player runs out of lives, but the player has infinite continues.
The weapons from M.U.S.H.A. all return, albeit with different colors.
Releases a barrage of bomblets, which explode upon impact with the ground or an enemy. The explosion persists for a short time after impact.
Causes the options that normally fly in front of the Aleste to encircle it in a protective shield. The options actively attack any nearby enemies.
Fires blue bolts of electricity that pierce through targets. It starts as two thin beams but upgrades to one, two, and eventually three thicker beams.
Flying Shadow Formation
Fires large shuriken in several directions. Initially fires in four directions, but this expands to eight directions at the higher levels.
The Aleste is temporarily invincible after collecting an item.
Upgrades the attack speed and power of the standard weapon. The initial upgrades add an additional beam in parallel, up to 4. The next two upgrades change the throwing knives into fireballs (first the outside two beams, then the inside two beams).
Equips the Aleste with the Exploding Flower special weapon or upgrades it if already equipped.
Equips the Aleste with the Ninja Star special weapon or upgrades it if already equipped.
Equips the Aleste with the Thunderbolt Ray special weapon or upgrades it if already equipped.
Flying Shadow Formation
Equips the Aleste with the Flying Shadow Formation special weapon or upgrades it if already equipped.
Boss: 飛竜 (鉄)
Boss: 武者王 (今川 義元)
Boss: (上杉 謙信)
Boss: 飛竜改 (鉄)
Boss: (武田 信玄)
Boss: (長宗我部 元親)
Boss: (島津 貴久)
Assault on Mouri's Palace
Inside Mouri's Palace
Boss: (毛利 元就)
Mid-Boss: 火竜 (鉄)
Robo Aleste versions of the game contain small balance changes to make the game easier. The big two changes are that dynamic rank does not rise as quickly, and that the yellow weapon has been buffed. The Japanese version also has a bunch of character dialogue stored as Red Book audio on the disc, but many of these tracks ended up being unused. The respective dialogues simply appeared as text.