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 Post subject: GD: Gemini Wing mechanics
PostPosted: Thu Jun 19, 2014 4:53 am 



Joined: 07 May 2007
Posts: 212
Location: Toronto, Canada
Here's some info I've put together that was gathered during TRP-STGT 2014, pretty much thanks to trap and his uber post. All of the tables were pulled from his work:
viewtopic.php?p=1020532#p1020532

Feel free to add/correct anything of course

Use a short-delay autofire
This is one of those games that benefit from fast autofire, as it potentially kills enemies faster for both a higher score and to keep you safe. Or use a longer delayed autofire if you want to play a little more fair, anything is good to at least avoid carpel tunnel...


It's a caravan, kinda
Similar to a caravan game, the faster you destroy enemies, the faster the next wave of enemies appear on the screen. This "enemy queue" is carried throughout the entire game. So for example, those red fireball things that appear only on stage 1 can actually spawn near the beginning of stage 2 if you don't destroy enemies fast enough.

However, the walled stages will always have the same enemies in the same places. Specifically, all of stage 3, the second half of stage 6 (including the short outside section), and all of stage 7. Also, stage 5 has a cloud section near the beginning that always spawns bats in the same place and a section near the end that has turret emplacements. These sections combine the enemy queue with the bats/turrets, although I _think_ it slows the spawn down a bit so you don't get too overwhelmed.


Bringer/Dropper bonus items and appearances (let's go with Bringer as the monster name for now)
Every so often, you'll encounter a creature that holds a bunch of gun-balls. One of the gun-balls might even be a speed up, bonus score item or even an extend. Unlike the standard enemy queue though, these Bringers look like they appear somewhat randomly. So what determines the gun-balls they carry, and when they spawn? Let's start with the concept of the "Kill Counter" and "Hit Counter."

The Hit Counter increases every time you hit an enemy/boss with a gun-ball. Gun-balls that hit multiple times (pretty much all of them but the Homing Missiles) will increment the Hit Counter for as many times the gun-ball attack hits an enemy. This Hit Counter does not increase with destroying rocks or vines in the walled stages, but the big plants in stage 6 will increase your Hit Counter if you hit it with a gun-ball.

This Hit Counter determines whether or not the next Bringer that appears will hold a bonus item, a speedup, score bonus, or an extend. Once the Bringer appears with the bonus item, the Hit Counter is reset to 0. If a Bringer spawns and you didn't make the threshold, the Hit Counter will carry over to the next Bringer until you get a bonus item. Bonus items always appear in a fixed order; see the section below.

The Kill Counter increases every time you kill an enemy with any attack. Like the Hit Counter, this doesn't include rocks/vines, but unlike the Hit Counter, it stops increasing during certain conditions. One condition is if there are any uncollected gun-balls lying around the area (whether it's a Bringer that is carrying them, a small larvae that leaves behind a gun-ball, or if you died and your gun-balls get scattered around ). Another condition is that you are nearing the boss, maybe 15 seconds or so before you get to it.

When the Kill Counter reaches a certain point, the Bringer will spawn and the Kill Counter is reset. The number of kills needed to spawn the next Bringer is fixed; see the section below.


Bringer bonus item and appearance queues
Here are the tables for when the next bonus item appears and when the next Bringer makes an appearance. NOTE: these tables are for Normal difficulty only! Apparently, each difficulty has a different drop/appearance table, and the default dip switch configurations set the game to Easy difficulty. If you want the tables for the other difficulties, either experiment or go through the game code yourself (or find someone who knows how =/). The tables loop if they reach the end. You can ignore the Flag, +W,H? and Motion columns.
Spoiler: show
Code:
Hit Counter Bonuses queue [repeats]
Hits |   Item   |
-----|----------|
   8 |    Speed |
   8 |    Speed |
  16 |   20'000 |
   4 |    Speed |
  31 |   50'000 |
  37 |    Speed |
  31 |    Speed |
  16 |    Speed |
  32 |   Extend |
  24 |   20'000 |
  32 |   50'000 |
  16 |    Speed |
  20 |  100'000 |
  20 |    Speed |
  20 |    Speed |
  20 |   20'000 |
  20 |    Speed |
   8 |   50'000 |
  35 |   Extend |
   4 |    Speed |
  16 |  100'000 |
  37 |    Speed |
  24 |   20'000 |
  32 |   50'000 |
-----|----------|

Kill Counter Chain Droppers queue
Kill | Flag | ItemSet | ItemCnt | +W,H? | Motion |
-----|------|---------|---------|-------|--------|
  76 |   E0 |      14 |       6 | 00,00 |      4 |
  38 |   E0 |       4 |       4 | 00,00 |      5 |
  47 |   E0 |       7 |       6 | 00,00 |      6 |
  37 |   F8 |      10 |       5 | 00,00 |      1 |
  37 |   E0 |      12 |       4 | 00,00 |      1 |
  35 |   E0 |       8 |       4 | 00,00 |      6 |
  37 |   D8 |      11 |       3 | 00,00 |      0 |
  32 |   E0 |       2 |       4 | 00,00 |      2 |
  32 |   E0 |       3 |       6 | 00,00 |      5 |
  35 |   E0 |       9 |       4 | 00,00 |      3 |
  48 |   F8 |      11 |       4 | 00,00 |      1 |
  50 |   F0 |       7 |       4 | 04,04 |      6 |
  56 |   E0 |      15 |       5 | 04,08 |      3 |
  63 |   C0 |       4 |       3 | 04,04 |      5 |
  76 |   E8 |       8 |       4 | 08,08 |      0 |
  76 |   E0 |       5 |       4 | 08,08 |      6 |
-----|------|---------|---------|-------|--------|


Manipulating the Bringers for bonus items
So what's the point of all this? Basically, in order to get the most bonus items, you'll want to balance the Hit Counter and Kill Counter together so that you spawn as many Bringers as possible and have each Bringer carry a bonus item. Check the tables to help plan your route.

A few ideas to help you plan:
-there is a bit of a stretch where you need a high Hit Counter in between the first and second 50K bonuses
-on the 6th bringer, if you've been maintaining bonus items, you'll notice that the Kill threshold is slightly less than the Hit threshold, so you'll have to keep an uncollected gun-ball on the screen for a little bit to keep the Kill Counter from rising while you kill a bunch of enemies with gun-balls
-use the MAME cheat, copy this into a file named gemini.xml in a directory named cheat and enable cheats by setting 'cheat' to '1' in your mame.ini:
Spoiler: show
Code:
gemini.xml:
<!-- Shows Kills, Hits, Droppers, Bonuses -->
<mamecheat version="1">

  <cheat desc="Watch Stats">
    <script state="run">
      <output format="K%d, H%d, D%d, B%d" align="right">
        <argument>maincpu.pb@(C031)</argument>
        <argument>maincpu.pb@(C032)</argument>
        <argument>(maincpu.pb@(C02F) BAND 7F) RSHIFT 2</argument>
        <argument>(maincpu.pb@(C033) BAND 7F) RSHIFT 1</argument>
      </output>
    </script>
  </cheat>

</mamecheat>


Bringer item probability
Each Bringer spawns with a different item set which also seems to be fixed. Compare this table with the ItemSet column in the Bringer appearance table above (NOTE: may also be affected by difficulty, this is for Normal). There's not really much you can do but just pray that you get a good set of gun-balls.
Spoiler: show
Code:
(Item Dropper refers to larvae)
'Item Dropper' odds:
  Spread [ 19%]:**************************************************
    Fire [  8%]:**********************
   Sweep [ 22%]:**********************************************************
  Spiral [ 25%]:*****************************************************************
  Rocket [ 17%]:*********************************************
  Extend [  0%]:
   Speed [  6%]:****************
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 0 odds:
  Spread [ 50%]:********
    Fire [ 50%]:********
   Sweep [  0%]:
  Spiral [  0%]:
  Rocket [  0%]:
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 1 odds:
  Spread [  0%]:
    Fire [  0%]:
   Sweep [ 50%]:********
  Spiral [ 50%]:********
  Rocket [  0%]:
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 2 odds:
  Spread [ 50%]:********
    Fire [  0%]:
   Sweep [  0%]:
  Spiral [ 50%]:********
  Rocket [  0%]:
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 3 odds:
  Spread [ 31%]:*****
    Fire [  0%]:
   Sweep [  0%]:
  Spiral [  0%]:
  Rocket [ 68%]:***********
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 4 odds:
  Spread [ 31%]:*****
    Fire [  0%]:
   Sweep [ 37%]:******
  Spiral [ 31%]:*****
  Rocket [  0%]:
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 5 odds:
  Spread [ 31%]:*****
    Fire [ 31%]:*****
   Sweep [  0%]:
  Spiral [  0%]:
  Rocket [ 37%]:******
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 6 odds:
  Spread [  0%]:
    Fire [  0%]:
   Sweep [ 50%]:********
  Spiral [ 50%]:********
  Rocket [  0%]:
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 7 odds:
  Spread [ 31%]:*****
    Fire [  0%]:
   Sweep [  0%]:
  Spiral [ 31%]:*****
  Rocket [ 37%]:******
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 8 odds:
  Spread [ 25%]:****
    Fire [  0%]:
   Sweep [ 37%]:******
  Spiral [  0%]:
  Rocket [ 37%]:******
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 9 odds:
  Spread [ 37%]:******
    Fire [ 31%]:*****
   Sweep [  0%]:
  Spiral [ 31%]:*****
  Rocket [  0%]:
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 10 odds:
  Spread [ 37%]:******
    Fire [ 12%]:**
   Sweep [ 18%]:***
  Spiral [ 12%]:**
  Rocket [ 18%]:***
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 11 odds:
  Spread [ 25%]:****
    Fire [ 12%]:**
   Sweep [ 18%]:***
  Spiral [ 12%]:**
  Rocket [ 31%]:*****
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 12 odds:
  Spread [ 12%]:**
    Fire [ 25%]:****
   Sweep [ 18%]:***
  Spiral [ 25%]:****
  Rocket [ 18%]:***
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 13 odds:
  Spread [  0%]:
    Fire [  0%]:
   Sweep [ 50%]:********
  Spiral [ 50%]:********
  Rocket [  0%]:
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 14 odds:
  Spread [  0%]:
    Fire [ 12%]:**
   Sweep [ 43%]:*******
  Spiral [ 43%]:*******
  Rocket [  0%]:
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

'Chain Dropper' set 15 odds:
  Spread [  0%]:
    Fire [ 12%]:**
   Sweep [ 37%]:******
  Spiral [ 18%]:***
  Rocket [ 31%]:*****
  Extend [  0%]:
   Speed [  0%]:
  20'000 [  0%]:
  50'000 [  0%]:
 100'000 [  0%]:

Gun-balls will change when you hit the Bringer, however there seems to be a bit of delay before the gun-balls change again. Try to kill it before the delay passes in order to get your desired gun-ball, or steal it if possible.


Tecmo-Land! 50K bonus
Shortly after exiting the vine area in stage 6, move toward the right of the screen and fire your weapon. If positioned correctly, you should notice that your shots hit something in mid-air. Keep firing at that spot and you'll reveal a picture of a mountain. Fire some more and you'll reveal Tecmo-Land, granting you 50K points and a neat little message. See: https://www.youtube.com/watch?v=ogLu18mEehk#t=16m25s


End of game bonus
The end of game bonus is 50K per life and 20K per gun-ball (maximum 15). Basically, don't die, arrive at the final boss with as many gun-balls as possible and milk the rest. Note that the game will not use any point/extend gun-balls for you, so if you arrive at the boss with any of those, prepare to milk a lot more (or lose points).


Killing the final boss
The final boss looks like a huge pain to fight. At first glance, it looks like you can only damage it when its tail opens up, and the only way you can hit it is with a gun-ball. However, this is time consuming, tied to luck if you don't have a good gun-ball, and it also means you'll lose 20K points since you'll be left with 14 maximum when you kill it. However, there is a way to hit it with your main weapon and go for a speedy kill.

After it "burrows" at the top of the screen for a moment, when it comes down is a good time to attack it. However, it looks like you can only hit it safely when it comes down the first time and then every other time after that. It's possible to do this with no speedups, but you'll probably be dealing less damage since it takes slightly longer to reach the attack point. It is possible to kill it outright on the first pass by hovering over the blue part before the shell is opened, but sometimes the boss spawns a larvae right before it opens its shell, killing you before you get to attack. Unless there is some way to manipulate it, you should probably wait in the corner for safety.

The position where you can actually deal damage is a bit tricky to find; you have to be a little in between the blue tip and green tail. Shortly after this opening, there is another window to attack the tail after it moves to the right and then to the left. This window is slightly easier as you don't have to mess around with proper Y-axis positioning; simply move to the top as far as possible and then move left toward the tail. See: https://www.youtube.com/watch?v=ogLu18mEehk#t=31m36s

You might think that shooting directly down the center from the bottom will work, but it doesn't seem to deal any damage. Too bad =/

A HUGE WARNING though: a larvae has the chance to spawn while you're hovering over the tail, instantly killing you. I don't know what the chance is or how to manipulate it, but all I know is it's happened to people. I've only EVER had it happen in practice and never in an actual run. Maybe one thing I do is restart MAME every time I do a run (Shift + F3 to reset recording input), but I don't think that does anything.

Another oddity: if you've used speedups, you can get yourself killed if you move into the bottom walls. However, if you have no speedups/have died recently, then you'll be safe...


Replays
https://www.youtube.com/watch?v=G0qlCqhTYjo - Jaimers clear on Normal difficulty with 1,941,910
https://www.youtube.com/watch?v=qF8kC4OqHRU - demonstration of killing final boss with main weapon on 1st/3rd passes


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 Post subject: Re: GD: Gemini Wing mechanics
PostPosted: Fri Jun 20, 2014 10:48 pm 


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Joined: 31 Aug 2009
Posts: 7749
Location: 東京都杉並区
Excellent write-up, thanks for turning my info post into something actually understandable :D
_________________
@trap0xf | daifukkat.su/blog | scores | FIRE LANCER
<S.Yagawa> I like the challenge of "doing the impossible" with older hardware, and pushing it as far as it can go.


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 Post subject: Re: GD: Gemini Wing mechanics
PostPosted: Sun Aug 01, 2021 10:41 pm 


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Joined: 26 May 2010
Posts: 47
Location: New Zealand
Thanks Kyper and trap15 for your excellent work here, it really gives a lot of insight into how this game works.

edit: does the bringer always spawn with 3-way/spread? not mentioned above but all the footage i've seen makes me think so.


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