This is the Gate of Thunder hint sheet.  (additions and corrections
should be sent to bt@cpac.washington.edu)

Level Select:  at the title screen press I, II, II, I, Select, I, II, I, II,
	       Select, Select.  Then press Run and at the bottom of the screen
	       you'll have a new item, "Stage"

Boss Strategies:

Stage 1 
Use lightning, and let your wingmen do all the shooting, just stay one
step ahead of the boss so that you can avoid his fire power.  You need
to shoot the area that opens up.

Stage 2 - "Asteroid"
Use either Earthquake or Lightning.  Shoot the boss's beak when it pops
out, then right before the laser that he shoots gets to you, move forward
to avoid it.  Reposition yourself and repeat.  When the circle stops 
moving, move to either the top or bottom of the screen in order to avoid
it.  Then start over again.  With Eartquake you can destroy this boss in
2 to 3 cycles.

Stage 3 - "Mine"
Position your self as low as you can and as close to the left foot as
possible.  When the cap drops, fire away (letting your wingman do all
of the work).  When the cap returns, quickly move away from the foot 
toward the center of the screen to avoid the firball.  Repeat.  With
Earthquake, this boss can be eliminated in 3 cycles.

Stage 4 - "Base"
Use Earthquake to destroy the upper half while avoiding the orange things
and the fireball volleys.  Once you have destroyed the top half (you'll
get some fire and explosions) change to Lighning and again avoid all
the horrors thrown at you.  When the top comes off, move toward the bottom 
of the screen and move in to shoot this boss's sweet spot.

Stage 5 - "Crown"
Use either Earthquake or Lightning.  You need to shot this boss in his open
mouth.  Stay even with his mouth (shooting the red clouds that appear at 
the bottom) and then avoid the oscillating white balls that are thrown at 
you (by moving to the extreme top or bottom of the screen).  Then stay
even with him as he unleashes the "White Fire" (which you can shoot).
Repeat.  With Earthquake you can destroy this boss in 2 cycles.

Stage 6 - "Dark City"
Use either Earthquake or Lightning (if possible).  The bosses patter is
this, shot volleys, followed by two fireballs.  Stay low and to the far
left to avoid the volley, then when the first firball comes toward you
you will need to move just slightly to the right to avoid its explosion.
Then position yourself so that you can shoot his "neck" (where the fireballs)
are coming from when it opens (and releases it's second fireball).  After
the second fireball is released, reposition yourself at the bottom left
of the screen and avoid the explosion when it comes.  Repeat.

Stage 7 - "Crown Core"
Use either Lighning or Earthquake.  First you need to shoot the "pods"
that are firing the white flames at you.  You can do this by moving in
a "C" pattern - going back and forth between the upper and lower ones
(I always seem to eliminate the top ones first).  Once they are gone,
the middle section of the ship will start firing bombs at you that
will explode on the same horizontal plane that you are.  Here you simply
need to move up and down, avoiding the explosions, and getting in as many 
shots to the center of the ship as possible.  Once this part is over, the
fireballs (from the corners) will stop and the ship will launch "fire
stars" at you, 5 at a time.  Simply avoid these stars again while
pummeling the mid-section of the ship.  That's it.

Hidden 1UPS:
There are hidden 1UPs in the following stages: 2, 3, 4, 6 & 7.
You need to shoot them first, before you run over them with your ship.
Sonic Boom is best suited for shooting them since they are generally
hidden behind otherwise impermeable walls.

Game Ending:
Pretty lame, and be on the look out for the misspelling of "again"
(no, it doesn't have an "E" in it. . .)