Iron Gate

Iron Gate is the first stage in the Dark storyline of Sonic Adventure 2 and the first stage playable with Eggman. It represents Eggman's attempt to infiltrate the GUN's military base.

Plot

Eggman accidently discovers about a top-secret weapon called “Project Shadow” on his grandfather’s, Gerald Robotnik's, journal. Thinking that Dr. Gerald is the greatest scientific mind of the world, Eggman thinks it’s a waste of good research not taking advantage of it. With this in mind, Eggman sets off to the GUN military facility, which is where the mysterious is according to the diary.

Level layout

Level divisions

Iron Gate is divided into five major sections, each a numbered level.

Eggman starts at Level 1, after busting the corresponding first doors open in the previous cutscene. In this section, the GUN robots are in Level 1 defense formation: Intercept intruder mode. The location starts with a long tight hallway and at the end, there’s another Level 1 door. After this, there's the first Point Marker and two rooms connected by a hallway beyond them there's another hallway, with the Level 2 door at the end.

After the Level 2 door, there is a shaft with a large elevator that will transport Eggman to a lower position, where another Level 2 door is, leading to a tight hallway that leads to the second Point Marker and another Level 2 door. Past this there's room, where item boxes are in the middle. There’s a hallway to the front hidden by yellow pressure containers, that leads to Eggman’s Laser Blaster and there’s a hallway to the right, with the Level 3 door at the end.

Continuing from the Level 3 door, the speaker will note that Eggman has breached section 3 to 8, and he’ll be in a large room. To the front and over a cylindrical tube, there’s a spring, which will lead to the Mystic Melody pedestal and from there to another large room, which is the same as the Switch room of Rouge’s Security Hall, although mostly empty. To the right there’s a trail of platforms that will lead to a bridge of some sorts, then another hallway, a second bridge and at the end there’s the third Point Marker, along with the Level 4 door.

After the Level 4 door there is shaft with another large elevator that will transport Eggman to a lower position, where another Level 4 door is, leading to hallway and to the Level 5 door.

Continuing from the Level 5 door, the GUN robots will switch to emergency defense mode and the a warning that the final security door will lock. There’s a room with Gun Hunters that will hover to Eggman to attack, then another Level 5 door, another room and another Level 5 door and then to a larger hallway, with a missile console system and the final security door, that will lock down as Eggman approaches it.

Enemies

• Beetle Series: Mono Beetle, Gun Beetle (Normal Mode), Gold Beetle
• Hunter Series: Gun Hunter (Normal Mode), Laser Hunter (Hard Mode)
• Hawk Series: Mono Hawk (Hard Mode), Gun Hawk (Hard Mode)

Locations

Ancient ruins

• In the room after the Level 3 door, accessible by a spring and a set of tubes: a spring appears, which will launch Eggman high enough to grab an upreel and be transported to a large room above.
• In the room above the room after Level 3 (see before), at the right aisle: platforms appear, leading to the high platform in the middle.

Animals

Animal	Number	Location
<iimg>Dragon!</iimg>	1	Level 3: On the right of the circular tube located after the Mystic Melody pedestal platform.
<iimg>Gorilla!</iimg>	2	Level 1: In the northeast corner of the room after the first Point Marker, close to the Chao container ledge. Level 2: In the next room of the second Point Marker, in the northeast corner.
<iimg>Rabbit!</iimg>	2	Level 1: In the southwest corner of the hallway, close to the Omochao and to where Eggman first begins. Level 3: Amongst the four item boxes and a Gun Hunter in a corner, before the first bridge.
<iimg>Skunk!</iimg>	3	Level 2: In the southeast corner of the giant elevator shadt. Level 5: Amongst the medical pack and extra life box, in the room after the first Level 5 door. Level 4: On the goal room, to the northeast.
<iimg>Tiger!</iimg>	2	Level 3: Close to the second yellow giant pressure tank, on the lower level. Level 5: After the ledge, in the room after the first Level 5 door.
Random	5	Level 1: In a pipe after the ledge, located at the second room after the first Point Marker. Level 2: In a pipe, located in the middle of the hallway that leads to the Level 3 door. Level 4: In a pipe, located in the giant elevator shaft, after the Point Marker. Level 5: In a pipe located in the room after the third Level 5 door. Level 5: In a pipe, located at the left corner of the final security door.
Total	15

The level specific animal (third Chao container) is a Dragon.

Big the Cat

In the first elevator shaft, stand on the bridge before the Level 2 door. Big is to the left, down in the shaft and hanging to the wall. Jumping will allow a closer look, but Eggman will die.

Chao containers

• Level 1: In the first room after the first Point Marker, on a ledge.
• Level 3: Amongst wooden containers in a side ledge, located just before the third Point Marker and Level 4 door.
• Level 5: On the goal room, to the south.

Gold Beetle

In the first elevator shaft, at the end of it to the right.

Lost Chao

• Upgrades: Jet Engine, Mystic Melody

Beyond the Level 3 door, there is a cylindrical tube with a spring. Hoover to it and jump to the platform to the right, follow the trail of rings and activate the ancient ruin. Hit the spring and let go of the pulley at the top, go to the right hallway, activate the second ancient ruin and follow the ancient ruin platforms to the higher platform.

Upgrade

Eggman's Laser Blaster upgrade can be found in this level - though it requires the Large Cannon to access. It’s in a hallway, located at the north of the room after the second Point Marker, hidden by yellow pressure containers and after them, a set of six steel containers.