The Alien Dephts, also known as The Alien Labyrinth (misspelled "Labryinth" in-game), is the third stage in Strider II and all its ports except the Mega Drive one, where it is switched around with the fourth stage.
Following the previous stage the Warrior moves underground in order to avoid the full force of a terrorist attack, only to find himself confronted with evil alien hatchlings. This stage is set inside an underground alien nest with organic-like green walls and grass-like floors that sprout alien hatchlings. Later parts of the stage show gray walls and round windows, and finally damaged wired walls. There are also pools of green seemingly acidic slime the Warrior must overcome by climbing above them.
The original stage is a maze of identical rooms the player must descend through by using chains hanging from the ceilings. The top areas of the maze have green organic walls and some pods, and later some strange tube contraptions. At times there are white ceramic walls with circular glass domes. The ground in lower areas displays plant-like vines, and the final stretch before the boss is filled with damaged walls covered in orange wiring. As stages before, there are several dead end paths holding power-ups for the robot transformation.
The Master System port altered the stage's appearance, giving it more bright colors and adding machines, large tubes and strange containers filled with liquid. A new obstacle is added in the form of a spiked press which goes up and down and must be slid under. The press can appear alone or in pairs of two, to difficult avoiding them. The bottom floor has a large pool of green water/slime that serves as another new obstacle. It must be passed by climbing over it, but globs of the substance will fly from the pool and go forward, throwing Hinjo into his death if the player is careless.
The Mega Drive port altered the background elements further, removing the computers and presenting large dark blue panels, piled up jars with some blue substance inside and metal wired walls. The spiked press obstacle is removed and while the pool of green slime remained, the globs jumping out of it only splash up and down. A few other smaller pools were also added. Dark green globs falling down from the ceiling were added as another obstacle.
Enemies present since the home computer originals include:
- Mutant Soldier HCO, MS
- Automated Sentry AM, AT, C64, MS
- Missiles HCO, MS
- Alien Head AM, AT, MD
- Alien Hatchling AM, AT, MD
- Boss: Alien Mother
Enemies introduced in the ports include:
|Strider II / Returns|
|Equipment: Cypher • Climb Sickle • Gyro laser • Rotun shield • Shurikens|
Moves: Slide • Cypher Attack • Elite Mechanical Combat Unit
|Alien Terrorists • Automatons • Wall Crawler • Wolf • Aliens • Turbo Wasp|
|Helios • Energy discharging skulls • Alien Mother • Milsoma • Podulous • Inferno • Waspini • Anti-Gravity Device|
Terrorist Leader • The Master
|The Forbidden Forest • Castle Metropolis • The Hive • The Alien Depths • The Master's Prison Ship|
|Lexia • Striders|