To kill the robot at the end of every second level,
fly at 2 1/2 units (in other words, with two blocks
of your altimeter filled in and one at halfway).
Shoot 6 shots at the robot's missile, and you will
kill it quickly. If you miss, either dodge the missile,
or keep firing and you can still blow up the missile.
However, you get less points for hitting the missile
while it's in the air.
Flying at an altitude of 1 1/2 will allow you to hit
ground targets while making their shots go harmlessly
Shoot airplanes on the ground: it will reduce the number
you need to kill in the space scene. If you shoot all the
airplanes in space you will get a bonus.
On the levels in outer space, start up the highest point
on the upper left and start shooting immediately. You
should be able to hit the satellite right away. If you
miss, keep moving to the left and keep firing. This works
for the second satellite also. This is important in later
levels because it is possible to run out of fuel in space:
if you hit the satellite, you will get some back.
There are only two levels that repeat. The first air fortress
level never gets much harder: use the same pattern for it.
On the other levels, only the gaps become narrower.
Always keep firing! This way you can see if you will make
it through the gaps, and you can adjust your height as needed.
On the outer space levels, you can tell if you're at the
same height as the enemy planes by watching the color of
their canopies. If the canopy turns white, you're at the same
altitude. This makes it much easier to grab the 1,000 point
bonus for destroying 20 enemy planes, as well as to avoid their
On later levels you will lose fuel quickly. Make sure you hit
as many fuel tanks as possible. If you run out of fuel you will
lose a ship.