Many of the 3-D shooting range stages contain hidden life units. Remembering where they are hidden will help you to reduce the damage you sustain in these difficult stages.
Life units follow you as the screen scrolls, so if you reveal one but don't need it right away, you can save it for later (though you will have to be careful not to accidently shoot it.)
In 3-D screens, only two life units can be visible on the screen at any one time (though in action screens you can have more). If, for example, a life unit follows you from a previous screen into a screen that contains two more life units, you could reveal one on the new screen, but not the last life unit until you used one already on the screen. (If two life units are visible on the screen and you shoot the area containing the third, it simply will not appear and you lose it.
Mission 1 Stage 2: Food store
There are three life units along the top row on the left side. Recall that you cannot have
more than two of them visible at one time. Be careful not to lose one. (There is another
one between the two pictured here.)
Mission 2 Stage 4: Electronics store
Mission 3 Stage 2: Warehouse
All four of these life units are hidden under distinctive gray "blocks" with a blue square in the middle.
Mission 4 Stage 6: Alien Spaceship
There are three life units on this screen. The one not shown here can be found in the block
that the cross-hairs are on in this picture.
This boss can be somewhat more difficult than the others. Although it only requires a few
hits to kill and does not attack, it moves very quickly and unpredictably. You will need to
be extremely patient to kill this one without taking any damage. Do not follow him if he is
walking away. He may turn around suddenly. Remember that you cannot move while you are
attacking. Wait for him to come towards you and try to line yourself up horizontally (at the
same screen depth) and learn to time your attack so that it will hit him but not let him get
close enough to trample you. Be patient and do not get discouraged if he moves and your
attack does not connect. (You will know if your attack is successful because a small yellow
explosion image will appear briefly in the spot where the attack connected.) Be ready at
all times to flip or speed-flip out of the way.
This boss is very easy. Stand back and learn the timing and range of his attacks. They are
the same every time. Use the speed-flip when you get trapped at the edge of the screen.
Once you are familiar with his attack pattern, position yourself in front of him so that you
will be just out of range when he attacks. After the lightning disappears, you can attack.
Then, either back up to give yourself room for his next attack, or speed-flip behind him and
wait for him to turn around. As you attempt to position yourself out of this alien's attack
range, remember that he is walking toward you. Err on the safe side if you're not sure where
to stand; if you are too far away to attack, you can always try again, but if you are too
close, you will take damage, which is a much more difficult mistake to correct.
This is the boss you face if you choose the left doorway at the end of the alien space ship.
Timing is the key. Again, you will need to familiarize yourself with the frequency of this
alien's attacks. Right before he attacks, use a flip to get behind him. You can usually
attack twice while he is stopped. Then be prepared to get out of the way if he turns around.
You cannot move while you are attacking, so make sure this boss has stopped moving before you
attack, otherwise you may not be able to get out of the way quick enough to avoid taking
damage. Do not try to attack from in front of him. You will either get hit when he punches,
or he will run into you.
This is the boss you face if you choose the doorway on the right at the end of the alien
space ship. You must learn the timing and range of this alien's attacks. When he attacks,
two small explosions will appear on each side. You can position yourself far enough away to
not take damage from the explosions, but still close enough that your attacks will connect.
Consider choosing the door on the left. To fight that boss, you only have to know the timing, not the range of his attacks. (Attacking from behind allows you a larger margin for error.) For the boss on the right, there is only a small area from which you can safely attack, making this boss somewhat more difficult.
With a little practice, you should be able to defeat all these bosses without taking any damage. After each one (except the green ones), you will be able to collect several life units. Use bosses as an opportunity to recover from the damage you have taken in the course of battle with regular aliens.
In 3-D shooting range screens, hold down the button for rapid fire. It makes these stages much easier.
Many aliens can attack by jumping toward you or firing a projectile at you. The best way to defeat them is to keep at different screen-depths than the aliens. Do not line yourself up with them horizontally until you are within attack distance, and be sure you attack first. For aliens that shoot projectiles, you should generally line yourself up, let the alien fire, move out of the way, and then line yourself up again and attack after you have dodged the projectile. After an alien fires, you have a little time before he'll fire again. Use this time to attack.
You can only kill one alien at a time. Therefore if there are two or more on top of each other, your attack will only kill one, leaving one free to attack you. Walk around, use flips and speed-flips to dodge aliens until you can safely attack them one on one. Try to draw one away from the rest and isolate it at one side or corner of the screen before attacking. Be patient when fighting. This game has no time limit, so take all the time you need to separate the aliens.
Save your special attack energy until the fourth mission. You will need all of it once you're inside the alien space ship.
After you defeat either end boss, the final stage is a 3-D screen (shown above). Do not waste time trying to shoot the alien brain. It has no effect. To win the game, you must simply survive this stage long enough to kill the fourth yellow alien that appears at the back of the room.