Walkthrough :
Level 1
Watch the introduction. Your character will be teleported and will reappear in water. Swim up. After surfacing, run right.

Kill all the crawling leeches in the next two screens, watching out for the ones that fall from the ceiling.

Run right, until the black carnivore leaps down. Immediately run left. Keep running left the chasm with the vine appears; then jump onto the vine. Your character will swing around one screen to the right. Run to the right (the black carnivore will follow). Keep running right, and your character will meet black shrouded aliens with guns.

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Level 2
After your character wakes, rock the cage left and right, while watching the guard change clothing. Keep rocking, and ignore his pistol shots and gibbering. The chains holding the cage will break, crushing the guard when it hits the ground.
Pick up pistol and run one screen right. Your friend will run off the right side of the screen, then run back. Kneel and fire a few shots off to the right, until the guard chasing your friend is killed.

Run one screen to the right, then wait on the far right of that screen, facing left. Your friend will go on to the next screen to the right. Your character must provide cover as he opens a door. Kill the two guards that will appear from the left.

Run right and wait for your friend to open the door. Go right, to the elevator platform, and wait until your friend gets on. Go up. In the dome, run to the right to view your character's location.

Return to the platform. After your friend gets on, go to the bottom. Run left and when the next screen appears, immediately duck and fire. Shoot the circuit on the left wall, and the glowing line will dim.

Return to the platform, wait for your friend, and go up one level. Go left and blast the wall away. At this point the gun will be empty. The guard below can not get out because the doors have been deactivated from below, but he will try to blast out. Ignore him. Go down, left, up, and to the next screen to the left. Your friend will always catch up. Stand on top of the small defect on the floor, and wait. Your friend will open the drain cover, and your character will drop down.

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Level 3
The trick here is timing, so practice is important. Roll left; there will be a steam blast ahead. Drop down and roll right; another steam blast will appear ahead. Drop down again between the two steam blasts, and roll right. Continue to roll in the most logical direction until your character drops out of the maze.

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Level 4
After your character drops out of the pipe, go left and recharge the gun. Blow away the doors to the right, then recharge the gun again.
Go right, until your character leaves the building. Kill the guard that is just outside the building.

Keep running right, until the chasm appears, then do a running jump to get across. Your character will land on a ledge on the far side. Shoot a hole into the wall on the right, and enter.

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Level 5
Your character is in the underground. Go down as far as possible, until a 'T' shaped rock appears. From here, go right.
The avalanches can be dodged with some patience. There is an obvious pattern in the falling rocks. (In the last area of falling rocks, and in the area where the tentacles are above floor mouths, your character can destroy the tentacle creatures. Kneel down and start a superblast, then stand up and release the shot.)

Keep going right; some of the ceiling tentacles may be shot to make them draw up for a short time. The others must be run under (they are too slow to catch your character when running). When the hole on the floor appears, keep running. Finally, your character will reach a wall. Blow it away.

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Level 6
Run left, dodging the creatures as before, until your character reaches the first room with the avalanche. The rocks are harmless when your character is on the higher ledge. Keep going left. A bat-like creature will be on the ceiling of the second avalanche room. Shoot it to make it fly, then carefully follow it to the left. In the next screen, the bat will fly into the tentacle creature's grasp, occupying its attention. Jump onto the stalactite, then to the next one, and so on. Your character may move up and down slightly on the stalactites. Jump off the screen to the left.

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Level 7
Your character will appear on the T shaped rock. Walk off the left side of the rock, and shoot the small piece of rock to the right that is holding up the main section of rock. Run up the newly created ramp, and to the right.
Keep running right, jumping over the holes, until a room with an overhead lake appears. Standing as far to the left as possible, blow away the lake support to flood the caverns. Run to the left. Depending on how fast you are, you can either do standing or running jumps over the holes. Keep running left until your character cannot go any further, and is standing on a platform in the rock. The water will rush up, propelling your character into the air. Run right, blowing away the intervening wall. Go up the stairs and run right.

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Level 8
Go one screen to the right, and while standing on top of the stairs, fire a shot. A guard will appear from the right side of the screen. Run back to the left and hide behind a force field. His force field will appear far to the bottom right, while he will appear at your level. Fire your gun when this happens. (This guard appears when your character is halfway across the floor area. Be ready to shoot and he can be killed when he appears without having to retreat.)
Go back left, down the stairs and right across the spillway. In the next screen, stand at the top of the stairs, shoot once and watch the chandelier fall. This will free your friend, who is trapped above, and will bring a guard from the right. As with the last guard, if it runs left to the next screen, put up a shield and wait, the guard will appear, but his shield will be several feet too low to protect him! (Before shooting the chandelier, your character may go to the middle of the room and fire two fairly quick shots to the right. The guard will appear after the first shot and will be killed with the second shot.)

Go left, back up the stairs, then right. Your friend will be gone, and if your character runs right one more screen, he may be seen sliding down a tube in the bottom left corner.

Go right. The guard that runs away upon your character's entrance in this area can not be killed. Follow the stairs down, and use the teleporter to get to the bottom part of the screen.

Go right. A guard will hit your character and the gun will be dropped. As the guard lifts your character, watch your body. Press fire when your head goes up and your character will kick the guard. Run left, roll onto your gun, and shoot the guard.

Go right one screen. Two guards will appear, one from the right, and one from the left. Move across until just before the guards appear, put up a shield to the right, move forward to make both guards appear, then turn around, and put up a shield to the left. Then, quickly kill the left guard with a super blast, turn and put up another shield to the right (timing is critical). Kill the remaining guard. All this takes practice, and perseverance.

Run to the top of the stairs, where the unkillable guard ran away. Run right and the guard may be seen hiding behind multiple layers of shields. Put up a shield before getting to the doors. Step forward just enough to open the doors, then step back and let them close. The guard will panic and release glowing spheres that can pass through shields. The spheres will bounce off the closed doors and roll back into the guard, killing him.

Run right, blowing away the door. There is a recharger in the next room.

There is a dome in the next room after that, with green globes reflecting a guard from beneath. Try to time it so that when your character ducks and fires, the guard will be underneath the globe whose chain is in your line of sight. Aim and shoot to kill the guard. If the shot misses, go out of the room and return. The guard should be back to his pacing. Again aim using the remaining globes, and when he is underneath, fire! Crash, and the guard goes down under an imaginary globe! (By watching the pace of the guard in the reflection of the globe, your character can tell when he stops. This is when he may be killed).

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Level 9
Return to the room where the two guards that attacked from both sides were killed. Go right until your character reaches a lake. This lake was created when the wall at the end of Level 5 was destroyed. The water that flooded the caverns rushed through the gap and flooded this area. Jump into the water, and swim down. Swim left at the bottom of the shaft. Your character should enter a room with two upward shafts and one downward shaft. Swim up the left most upper shaft and breathe from the air pocket that it contains. Then, swim down, and then down again into the downward shaft. Go right. Avoid the creatures and shoot the glowing line on the wall to the right.
Return all the way back to the top of the lake (do not forget to use the air pocket again).

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Level 10
Go right, and fall into the gap in the floor. Immediately blow away the right wall. Ignore the shots peppering the air around your character, and run to the right. The doors will close behind just in time to save your character from being shot.
A dead end will eventually be reached. Put up a shield to the left. Blow away the guards that will attack and wait. Finally, part of the ceiling will open, and an arm will wave around. Stand under it to be rescued by your friend.

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Level 11
Your friend will run to the right; ignore him and run to the left side of the screen, then right onto the ledge that appears to be part of the background.
Your character will pass behind a building. Notice that your friend has been captured. Leap off the ledge at the right side of the building. Run left, into the building. If done quickly, your character can run forward enough to use the shield that will already be there. Kill the guard standing behind it. Your friend will kill the second guard after a quick struggle.

Run right, and make sure your friend is in the lead. Stop when the edge of the chasm is reached. When your friend beckons, run at him, and he will toss your character across. Your friend will fling himself after your character and slip off the ledge.

Jump left off the ledge. After falling a bit, your character will grab an awning and swing onto a ledge. Put up a shield and kill the guards that appear from the left side of the screen.

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Level 12
Run left as far possible, until a room filled with fleeing aliens is reached. One will be locked out. Walk up to the door separating your character from him, and stop when it opens. Pull out the gun. The alien will surrender, and hit a trigger that locks all the doors on the screen.
Run to the right, then up the stairs. At the top, jump to the far right side of the screen, and put up a shield to the left. Blow away the wall between your character and the guard at this location. Allow him to keep tossing at least four blue glowing spheres down the stairs, then kill him.

Run left and use the teleporter. In the level below, face right and power up the gun for a superblast. The guard to the right will blow away the door; release the superblast to blow away his shield. Then, just use a normal shot to kill him.

Use the teleporter to go down, shoot the blue glowing line on the right wall, then go back up. Head down the stairs.

At the bottom is a hole, blown in the floor by the blue glowing spheres. Fall down the hole and run right. The next room is dark. Run right, ignoring the laser shots, and jump when your character reaches the far right side of the screen. (The next screen has a hole in the floor just as it is entered.)

Pull the lever and then drop through the hole in the floor that was just jumped over. In the chaos below, ignore everything and run right. Ignore the lasers shooting past your character. Eventually a teleporter will appear that should used to go up.

Go left and rescue your friend with the extending bridge.

Run right. Watch what your friend does in the strange wall marking, and repeat his actions. Follow your friend to the right.

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Level 13
The Tank. Hit all the buttons.

The buttons will perform the following actions: single missile fire, all missiles fire, side guns out, front guns out, lights on, power up, emergency buttons (including the escape pod), side guns in, front guns in, earth tremor on, earth tremor off, all weapons off.

The only way to escape is to find the button to activate the escape pod.

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Level 14
This is the final level. Run right. Kill the four guards on the next screen.
Run right and meet your friend. Your character will fall off the ledge. A guard will pull you up and start fighting. Your friend will appear and fight with the guard. Crawl to the right.

Wait until the guard is about to step under the sky light and press fire. Your character will pull a lever and the guard will die.

Pull another lever and crawl left. The first two barrages of lasers always miss if your character freezes when they fire. The third always hits. When your character crawls into the light, teleport up. Crawl right and collapse. The ending animation will begin.