The Forbidden Forest is the first stage in Strider II and all its ports. The name was first used starting with the Master System port, with the original home computer version simply referring to it as a "forest area".
The Forbidden Forest is a dense forest area located outside an enemy stronghold. The forest is found next to a warehouse built inside a cavernous area, but whether "stronghold" refers to this area or the next stage is unknown. There's also a spaceship in the middle of the forest, presumably the one used by The Warrior to reach Planet Magenta.
The original version is a very plain stage: it consists of a straight forest area followed by a short warehouse area. There's a spaceship in the middle of the stage that can be optionally visited. The spaceship is accessed through an elevator, consists of three floors and a second elevator and only contains power-ups for the robot form. The warehouse area is very short, consisting of two elevations before the boss battle begins. Chains are spread around for the player to climb, but some have contraptions that can hurt them.The Master System port altered the stage significantly: the forest area now has branches the player can climb and stand on and where items are hidden away. The spaceship has been merged into the main path, making it no longer optional: the player enters from the top, goes through the front cockpit and leaves through the elevator on the lower area that's now set over a bottomless pit, requiring a precise jump right to continue. The entrance to the warehouse is now separated by a pit as well, requiring climbing a tree and jumping right. The area has now a single, longer ascending and descending section before the boss room, which is now plain instead of unevenly raised.
The Mega Drive port kept most of the Master System design intact, only making the pit before the warehouse larger and adding a rope at the top to cross it, removing the pit below the fortress' exit and making Inferno's boss room much larger and with several platforms.
Enemies present since the home computer originals include:
- Mutant Soldier HCO
- Automated Sentry AM, AT, C64, MS, MD
- Genetically advanced plant
- Missiles HCO
- Mecho Bird
- Milsoma AM, AT
- Boss: Helios
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|