ST: Calling all Air Duelists: Shot power, rank, and you!

[Ed Oscuro]

Air Duel is a cute-em-up by Irem apparently intended as a movie tie-in with the 1988 animated film Akira. It is the kind of game that desperately needs Quickshot! bonuses.

There are two types of aircraft you can select in the game - here I only refer to the fixed-wing jet. Indeed I have not tested any of this with the helicopter; it has its own wonky-looking shot type which appears more rapid and might be better for endless point blanking.

When you start playing the game you immediately notice that there are many levels of fire. The progression goes like this:
Default with small "laser missile" ->
double fire (after one powerup) ->
double larger laser missiles ->
trident-formation (one large center missile, two smaller ones to the sides; after three powerups) ->
double wide shots (after four powerups; this is the level at which at least some enemy behavior and durability changes) ->
triple wide shots ->
quadruple wide shots (the seventh level, after six powerups) ->
Additional powerups collected reveal no extra shot power and add 1000 points.

The higher levels of fire are excellent at brooming up popcorn even near your sides (assuming the shot limiter doesn't mean they approach you at a moment your cannon has running dry, that is) and can sweep a lot from ahead of you. The trident formation does a reasonable job brooming up a number of enemies in one shot, but not as good as the higher levels obviously.

There appears to be two forms of rank in this game:
1.) More aggressive and rapidly firing enemies after the loop, and
2.) Increased enemy durability and attack patterns. I am going to talk almost exclusively about this second type, because the first type isn't avoidable. (However, keep in mind that the faster-firing enemies from the loop might change some of the strategy implications of what follows.) The durability and attack patterns of selected enemies are tied directly to your highest-reached shot level but does appear to reset for unrevealed enemies on player death, and I doubt enemies gain durability or attacks if you pick up a shot powerup after they have appeared.

Evidence I have for this theory:

The first boss: There are two behaviors for the first boss (before the loop): One in which its central gun fires the easily-dodged eight-way shot once during its attack sequence, and one in which it fires it twice. The eight-way gun fires twice when you have reached it with the maxmimum power level available at that point (the wide double shot, or the fifth level - four powerups collected). It fires once when you reach it at less than the maximum level available, i.e. up to the trident powerup level (the fourth level - three powerups or less). It doesn't appear to have more, or at least much more health at the highest powerup level. If you reach the highest level but die before the boss appears, it will only fire the eight-way once.

Scoring note: Note also that no matter your powerup level, the maximum points for the stage appear to be fixed at 38,800, or 58,800 after the clear bonus (during the intermission). The tiny tanks and the four aimed cannons along the back of the boss (the last two only appear late in the boss encounter, i.e. if you wait on attacking the boss' weak point) do not add any points, so killing them only provides a convenience. The regular tanks that roll out of the boss are worth the standard 100 points each, however. In other words, the boss itself is worth nothing - just clearing the stage. I have no information on whether this will allow easy boss timeouts later on; it seems possible, but I do notice that the first boss moves down the screen and that reveals more weaponry. In fact, I haven't explicitly seen that it times out (although I think it does).

The large tank from stage one: This tank type shoots tightly-spaced (by Air Duel standards) streams of pinkish bullets, and homing missiles from its back after you destroy the turret. When you first encounter one near the beginning of the first stage, your maximum powerup level is the small double shot, and you can pick up another powerup while the tank is onscreen to get the larger laser missiles (the third level, after two powerups are collected). This tank's turret is destroyed very quickly and the chassis follows in only a few more shots. Later, you will see more of these tanks working in concert with turrets (in Stage 2), small battleships (in Stage 3), and with up to two other tanks and assorted popcorn harassment, so dodging their combined fields of fire can be difficult enough to give pause. More importantly, you will find that it can take a long time to destroy the later tanks.

I made a similar observation as before about the single tank from stage 2, which fights while retreating up the screen at the same time the many small (and very weak) gray turrets are giving it cover with aimed shots. It appears to go down significantly easier and quicker if you reach it at the trident formation, and harder if you reach it at a higher powerup level - exactly like the previous boss. I did not confirm whether the cutoff for its additional power is exactly the same as the second boss, which would be useful to know.

Many bosses do not really seem to be bothered by extra shot powerups. The twin bosses at the end of stage 2 did seem to take a long while after reaching them at full powerup level and then dying once, so that I fought at the lowest powerup level, but they don't seem to take very long with either the trident laser or a higher level weapon (if you stay alive). The submarine boss of stage 3 seems to go down quickly if reached with either a high or low powerup level, and I actually noticed the aimed shots from its missile silos (not the large missiles that come from the back of the submarine and offscreen) more when I was fighting it at a lower powerup level than when fighting with a high powerup level. Most bosses, in the first loop, are pretty laughable no matter how you reach them. Meanwhile, the two minibosses in stage 7, and the final boss itself with its random-seeming attack pattern. Overall, in the first loop a high powerup level does not seem to be a hindrance against bosses.

More power is still more power: Places where you will notice a lower powerup level handicaps you are at the stage six enemy rush (you can kill some of the wedge-shaped dark gray planes from a high powerup level, certainly max, and bombing), and anytime there are massive amounts of enemies onscreen, because the wide shot of the max powerup will broom them up very quickly and decrease the amount you will have to fly side-by side to kill them.

The long and short of it:

A low powerup level may help manage large tanks, especially those working alongside other enemies - both in terms of speed to kill, and possibly in terms of what they throw at you.
A high powerup level makes large portions of the game significantly easier.
At max powerup level, extra powerup pickups grant the player 1000 points each (I believe; don't think it stacks from 500 -> 1000 or anything, although I'm not sure of this).

A simple strategy suggestion may be to conserve powerup levels past parts of the second or third stage, but on the other hand a reliable no-bombing strategy may be found to clear those areas as well. By the time you get to places where there are two or even three tanks working together, you will definitely be losing many points from missed popcorn waves (on top of the max powerup pickup bonus) and greatly increasing your risk of getting tagged by them, probably far past what you get from decreasing the durability of large tanks (which will still be challenging in numbers). Overall, if you have to make a choice, deal a bit longer with the few tough areas with multiple tanks working together and clear out the popcorn with the max powerup level.

Unanswered questions:
Is there only one transition for enemy strength in response to rank? It seems as if there may be three levels, at least, for the large tanks, or maybe it's just that extra powerup levels past the level five (four powerups taken)'s double wide shots have somewhat diminishing returns in damage production.

What are all the enemies with additional attacks and durability, and at what levels?

Some enemies which gain durability from a higher powerup level:

Large tanks
The stage 1 boss and certainly some subsequent bosses
The large gray missile emplacements (i.e. non-animated, gun-free turrets) that fire four missiles diagonally - they are very weak on the lowest powerup level, but can soak up many shots from higher powerup levels
The fast battleships in stage 3 (however their shot patterns are still easily predicted at max powerup and easily led so that you have plenty of time to evade).

Some enemies which do not seem to gain durability from a higher powerup level:

The wedge-shaped enemies that appear in the enemy rush wave in stage 6 (at least those before the really big fast planes start moving down the screen) appear to be nearly impossible to kill, even using a bomb, at the low powerup levels; however, at the max powerup level you can take at least a few out using bombs and fire. Each is worth a fair number of points so this might be worthwhile. I am not sure about the really big planes that are nearly half the screen wide.

The white / blue enemies that shoot two shots straight downwards that your jet can barely squeeze through, and which appear a bit like item carriers, didn't seem much more durable at higher powerup levels, taking roughly the same amount of time to kill as from lower powerup levels (I think I managed to kill more at max powerup level than at the lowest level).

(mod edit - fixed thread title)
Ed edit: Fixed a typo in the "evidence" section, added a couple more thoughts on scoring in the next, rewrote the first "unanswered question" to be intelligible.

[Despatche]

thanks for this, i was hoping i wouldn't have to avoid powerups. popcorns bother me way more than large ships anyway

[Ed Oscuro]

Thanks for the feedback. I edited a few things because my writing was atrocious in places and was obscuring the point. I think I might need to rearrange this to put the most important parts up top, and the gory details later (if I preserve them at all).

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