The second stage employs a 3D perspective as the players move through the internal passages of an enemy base. To proceed through the base, you must destroy the power core seals placed at various points on the door, and then run forward to the next room. If you try to advance before the core is destroyed, you will hit the high-voltage current and become temporarily paralyzed by the shock, leaving you vulnerable to attack. Defending each room are turrets which are placed on the doors themselves, soldiers, and grenadiers. Two kinds of soldiers appear; standard soldiers and soldiers which provide weapons. Standard green soldiers compose much of the defense and provide only points when shot. Red soldiers provide a weapon or power-up when you shoot them. Only one such soldier will appear in each room.
Grenadiers are a big danger. Kill them as fast as you can or they’ll start tossing grenades at you. Rolling mines also pose a threat.The best way to deal with the rolling mines is to duck and shoot at one until it explodes, or move between two of them if there’s a space. The other way is to jump over them, but it’s dangerous to jump straight up above them. Instead, it's a better idea to jump to either side so that you don't come back down and land on them. Crouching on the ground will protect you from any gun fire. If there’s too much action on the screen, simply crouch and wait for the gun fire to die down. However, don't wait too long if grenadiers appear. Once it's safe, stand up and continue firing.
- Room 1
- The seal is level with you’re gun so focus your shots at it until it explodes. You won't encounter much resistance here.
- Room 2
- The seal is on the left and a turret is on the right. Destroy the turret first, then go after the lock. Soldier appearance should remain light.
- Room 3
- The seal in this room is low to the ground. Crouch in the center of the room, and fire away until the seal is destroyed. Don't bother with the turrets.
- Room 4
- The seal is level with your gun, but there's a turret above it. Rolling mines will occasionally appear from the slots below the lock. Stand aligned with the lock and fire away. Once the rolling mines start appearing, crouch down and shoot the one that is threatening to hit you. Don't bother with the turret, but do crouch if it shoots at you.
- Room 5
- The final room shouldn't be too difficult, even though it's well defended. The best way to destroy the seal is to destroy the two turrets to the right and left of the lock, then concentrate on the lock itself until it blows up. The upper turret takes more effort to destroy, and is better left alone, but you must remember to crouch when it shoots at you.
Boss: Terminal 1
The boss at the core of the base is fought in a similar manner to your progress through the base itself. You can only move left or right and fire upwards. As soon as you’re able to move you should quickly head to either side of the room, in an effort to avoid turret bullets. Once the turrets start firing, stand below the closest turret, and stand as close as you can without getting hit by the bullets. You can only harm the turret when it is open. After you destroy the first turret, cross the room and attack the second one in the same manner.
Once the turrets are destroyed, focus all of your fire power on any remaining power seals. Once those are cleared, the boss will appear in the black section at the top of the screen. It attacks by firing large rings of fire at you. If you have the Spread gun, simply stand in the middle of the room and fire at it. None of the rings should get close to you. If they do, you can move out of the way. If you don't have the Spread gun, you will need to move around a bit more in order to dodge the rings. Unless you need to move, stay in one place and fire up as rapidly as you can until the boss is defeated.