Current personal best on one credit of Normal mode is Loop 2, Stage 8 with 2,968,600 points. Score extends seem to go to every million once you get the 1.5 mil extend? I got another one at 2.5 from what I saw. Here's a video of the run:
https://www.youtube.com/watch?v=BdD4m2Mge8kDIFFICULTY DIFFERENCES:Normal is the default. Easy mode appears to have fewer, slower shots, whereas Hard has a more, faster shots. The most significant change though is the difficulty mode appears to adjust enemy health. Hard mode makes it tough to kill certain enemies in a timely fashion, which can mean you risk being overwhelmed if you try to kill everything. Sometimes you have to focus on evasion until an enemy goes away.
There doesn't appear to be anything like dynamic difficulty or rank in the game. Difficulty in each stage appears to be tied to what difficulty you're playing and what stage you're at. I'm not currently 100% sure how difficulty in the loop works, but I think it's more tweaked then simply bumping the game up to the next difficulty level.
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HOW TO SCORE:There's a lot of score extends in the game which means scoring can directly assist with your survival. It's possible to get to the final boss with under 1.5 million, thus missing a potential 1UP you could get in the first loop (the 2.5 million extend is pretty much only going to happen late in loop 2 though). There's three major ways to score:
• Destroy stuff. Self-explanatory.
• Collect hidden point items. Find hidden shootables and uncover them for various bonuses. Ice cream cones are the biggest ones I've found, giving a whopping 10,000 points.
• Collect equipment for your ship when you are maxed out on that equipment. Collecting bombs when your stock is at 7 is 8000 points, collecting a shield at max shields is 5000 and goes down according to how much shielding is left when you recollect a shield, collecting gunpods when you have 2 is 5000 (?), collecting primary weapons when you are already using that weapon and at max power is 5000 (?) and collecting secondary weapons when you are using that weapon and already max power is 2000.
In a lot of stages, there are fixed weapon powerups floating around. For instance, in stage 1 there are several guaranteed Red, Teal, and Blue primary weapon orbs. In stage 2, you'll encounter 3 floating Silver orbs at one point, encouraging you to switch for scoring purposes. Collecting them repeatedly is an important way to score and thus the game often encourages you to swap to specific weapons to collect multiple orbs in a row for score. Note that in some instances the weapons they're offering you are terrible for what's upcoming, and in others (such as the stage 5 boss's brown orbs) they're incredibly useful for where they're given.
Because there's a huge reliance on knowing what weapons are useful where, I'll detail that in the stages as well as bosses. Note that one of the challenges of the game at times is dodging the slowly floating weapon orbs. The secondary missiles you have at any given time don't impact you too much so if you accidentally collect one you didn't want it won't be a huge deal, but accidentally grabbing an inappropriate weapon at a bad time can make things tricky. If your weapon makes a section difficult, you can always play defensive and focus on avoiding enemies rather than trying to kill everything.
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WHERE IS THE HITBOX?The hitbox in the ship is quite small for a DOS era shmup. It's a rectangular box in the middle of your ship about the same vertical height as the nose section at the front of your ship. It's positioned in the center of the ship's body and extends from the back of the ship about up to where the neck of the ship starts. I'll have to test more thoroughly and draw an overlay showing hitbox location.
Stage 1 has a miniboss enemy designed to show you how small your hitbox is, where you can sit in front of it and easily squeeze between two thin shots it fires. It's not quite bullet-hell style couple pixels small, but it's definitely on the smaller side for this kind of game and is downright tiny when compared to something like Darius.
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GENERAL ADVICE• Avoid the screen edges. This is absolutely not a shmup where you can hug the left side of the screen at all times. Stuff can and will pop in to ram you. Try to stay in the middle of the screen where possible until you learn where enemies can appear.
• Bombing is always preferable to getting hit, even with a shield active unless you know a shield is coming up. Bombs are generally easier to recharge in this game.
• Learn what can be blocked with your gunpods. There's a ton of large projectiles in the game that can be completely nullified if you block them with the gunpod.
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WALKTHROUGH
STAGE 1:An easy level allowing you to learn the game. There's sufficient items for two players to max out shields, gunpods, and primary weapons at the start of the game. You'll be able to max out bombs later on by stage 3, so don't be afraid of using bombs early as you learn the game. You can use pretty much any primary weapon you want in the stage, though the drops here favour Red, Teal, and Blue.
There's a miniboss enemy that uses lightning that essentially serves to teach you about the sheer potential of your ship. It fires twin beams of energy that your ship is small enough to easily squeeze between them, and it later fires lightning blasts that your gunpods can block completely when aimed forward. Just get in front of it and fire away and it'll go down effortlessly.
The boss isn't terribly difficult. Just be prepared to get behind it when it pulls its legs in and rushes you. The back laser cannon has a bomb item and is most easily destroyed with the Teal weapon, getting close enough to hit it with the orbs and one of your gunpods.
STAGE 2:If you have the cyan weapon early on it's ideal for the large ships that come from behind. They launch missiles above and below that travel vertically, then when they're the same height as you launch towards you. They have an exploitable blind spot directly behind them above them where you can hide below the height of the missiles they fire, but in a position where your lower gunpod can block their lasers fired from behind.
For the rest of the stage, grab the silver orbs when they appear to score some easy points, then use whatever you want. Orange or red weapons are ideal for the asteroid heavy area. Don't be afraid to bomb if the seemingly invulnerable mines come out and try to ram you (they're VERY fast). The next level has tons of recharge items.
The boss is easiest with the orange weapon. Its stuff isn't too tough to avoid and you can actually squeeze in between its middle shots. Eventually it fires a concentrated laser stream with homing mines launched at you - I think these can be avoided if you're close to it so they can't swing around but it's way easier to block the homing mines with your gunpods. Sit about 2 ship lengths from the left edge of the screen right in the vertical center of the screen and they'll harmlessly fly into your gunpods when they're positioned in front.
STAGE 3:This stage features three distinct sections: 1) the slow section with various obstacles and smelting equipment, 2) the highspeed section against three large enemies (first one, then two at once), and 3) the remaining part of the stage over open lava.
For the first part of the stage, you can use just about any weapon you're comfortable with, though Teal helps with the small enemies that spawn around you. Watch out for falling pieces of equipment and lava being dropped on you, though. The important thing is to get the 1UP located at the bottom of the screen inside a portion of the stage. You have to bomb your way in and then out again (or take a shielded hit) in order to navigate it safely. There are several bomb items to obtain here though and at least one big enemy that rotates shooting a flamethrower that drops a bomb (as well as explodes into smaller enemies) when destroyed, and you can refill on bombs later in the level, so it's worth bombing here to safely get the 1UP.
The second part of the stage requires a decent frontal weapon to kill the large enemies in a timely fashion. They always follow a pattern of using the same three attacks one after the other. Block the initial bullets with gunpods, get in front of them when they fire the black orbs, and move up or down before the laser beam comes out. In spite of their size, Brown's phase missiles do not seem to work well as the high scroll speed causes many of the hits of the blast to whiff. Use Orange, Red, or even Teal weapons to deal maximum damage at the points where you can get in close.
For the third section of the level I use either Teal or Red. Powerups appear at the top of the screen and it's much safer at the top as there are enemies that jump out of the lava as well as these disc-like enemies that vacuum up lava in a kind of tornado as they move along, hitting you with the column if you don't destroy them fast enough for the column to drop back down. The hard part here when hiding up at the top of the screen is avoiding having a small enemy spawn on top of you. Eventually you'll reach a section that has a shield item, and after that there's several flamethrower enemies that drop bombs. You can refill on bombs easily even if you have to use a bomb here and there to destroy the sheer number of flamethrowers.
The boss is relatively trivial. Orange weapons are given to you at the top of the screen right before it and are the optimal tool. Get in front of it during its first phase, then hide near the top to destroy the projectiles as it starts spinning. It follows a pattern of hopping in from the sides of the screen but can be killed relatively quickly by its second phase where it fires lines of flames at alternating angles by exploiting a safespot at the bottom left of the screen. Hug the left of the screen and position yourself directly above the lava and it should die without fuss.
If you dawdle it'll also do the same spinning attack from the left hand side where it's harder to safely shoot down the projectiles without bombing, and at one point in its pattern jumps straight up from the middle of the screen and back down, sending waves of lava upward you have to avoid. But you should destroy it well before these show up.
STAGE 4:It's an underwater level! But there's no physics changes to the movement, so it's just business as usual. The screen doesn't scroll up or down at all, similar to Stage 2, but there's a good deal of enemies that come from behind at spots, so it's important not to hug the screen edge.
The miniboss isn't too hard to deal with - hide along the left edge of the screen and move between the spreadshots. Just about any weapon will work on it, with Orange, Red, and Silver being optimal picks.
The hardest part of the level are small plants that shoot a thin, difficult to see projectile. The projectile shots travel upward, then when level with your ship will stop for a split second and then fire towards you. Make a tap dodge up or down when they're going towards you to avoid them. The T style missiles are a good secondary weapon here for the level.
There's an opportunity to switch weapons before the boss later on in the stage. Red, Brown, or Orange weapons are ideal. I prefer Orange because it's easiest to shoot down the homing orbs the boss launches as well as the enemies it summons, both of which are its scariest attacks. In the boss room are Teal orbs and several O type missiles. The O type missiles can all be collected to get extra points, they're not useless here and they are helpful during the next stage. The Teal weapon however sucks against this boss so I would not collect it.
Note that even with a strong weapon you will still have to face most of its nastiest attacks. Expect an extended fight, bosses from here on tend to stick around. Its pattern is:
• Fires a spread of blockable yellow bullets from its upper claw, then does the same from its lower claw.
• Launches a homing orb. It takes a LOT of hits to down this and it's only realistically doable with a few weapons. Whether or not you manage to quickly destroy it, it then fires a static spread of thin lasers. These appear to be blockable, but if the orb is active it's tricky to get between them.
• Launches two more homing orbs that chase you for a while before going offscreen as it then burrows into the top of the screen, raining debris.
• As it digs in, a destroyable section at the back fires a spread of blockable bullets from the back.
• It then pops out of the ceiling, raining more debris. If you destroyed the claw, you can actually get parallel with it and hit it directly here with straight weapon. It then summons destroyable enemies and then starts firing those lasers that travel vertically then horizontally you had to deal with from those plants earlier in the level.
• It does the same dig into the ground and popping out again sequence, except going into the bottom of the screen instead the top. Pattern then repeats from here.
STAGE 5:The stage alternates between two different style of segment. One where you're travelling down a shaft, and one where you're scrolling at various diagonals with exploding pipes around you. Generally in the vertical shaft sections stay low to the screen to avoid enemies dropping on you and hitting you, or stay at the far left edge of the screen where there's a blind spot in the most dangerous enemies dropping. These sections aren't easy, but they're far from unmanageable.
The Teal weapon combined with the O or H missiles are recommended for the stage. There's also several drops for these guaranteed in the stage. Also note that Red and Orange are also suitable picks. The Silver weapon's not too bad either. The Blue weapon fires a bit slow and thinly, but you may prefer its 8-way screen coverage.
The real challenge is the lack of resources and the sections with the pipes. The two shield items in this stage are both in the first of three pipe sections. There's a couple bomb items in the stage and that's it. You have to go a long time without additional shields, so don't be afraid to bomb aggressively.
In the pipe sections, these giant spiky enemies appear and fire shootable bullets all around them. When they're in front of you, many of your weapons will destroy them quickly, but when they're behind you, it's hard to kill them in a timely fashion. Don't be afraid to use bombs to manage the screen. On top of these enemies filling the screen with shots, you also have to watch for exploding pipe. They fire 3 chunks of debris that fall rapidly and are a dark brown, which makes it hard to visually identify on the even darker background. This stage is a huge difficulty jump and there's no real trick here I've found except to try and learn the appearance of where enemies appear, when and where the pipes explode, etc.
Don't be scared when the boss drops down - you're guaranteed to get Brown weapon orbs before it, by far the best weapon against it, and it's a boss where using the weapon is relatively easy. Just hold shoot and you'll be close enough to hit.
When the boss drops down, hide at either the bottom left or bottom right corner where there's an initial spot gap in its legs, then slowly work your way up the screen and then back down the other side of the screen, destroying the flashing portions as you go. Brown's gunpod weapons will make short work of the ones you have to destroy from behind. The boss meanwhile fires flaming rings at you. The ones fired singly are not blockable, but the ones fired as spreads (which look identical) are blockable.
When all four leg sections are destroyed, the entire legs become one gigantic hitbox that you can destroy as the central core, the real fight, becomes active and splits from the legs. Destroy the legs, then get in front of the core with the Brown weapon to speedkill it in a couple seconds before the core gets to do anything. If you can't speedkill it then its pattern is:
• Swirls around in a tight circle firing downwards.
• Launches itself towards you, attempting to ram you several times.
• Goes to the middle of the screen and into the background in an unhittable state, launching a fixed pattern of attacks into the foreground.
STAGE 6:Red is a good general purpose weapon here. Teal and Silver also will work well. Watch out for enemies rushing you from behind, above and below. Do NOT stay against the left edge of the screen whenever possible.
The jumping enemies early on have a lot of health but drop bombs when destroyed (or gunpods if you have no gunpods). Later on there's enemies walking along the ground that only have a weakspot directly you can hit when above them or with a piercing weapon. Their attacks aren't too difficult to avoid, alternating between a spread of blockable mines and two piercing, unblockable aimed shots, but they have tons of health in addition to the shielding and are hard to actually kill. You may get better results just trying to avoid them, but well placed phase missile shots with the Brown weapon work if you're able to switch to Brown before meeting them. This also helps with the boss, who is weak to the Brown weapon.
There's a shield late in the level, but don't be afraid to bomb in order to safely collect it. Don't attempt to grab the gunpod right before the boss. It's a trap and the ceiling will fall down and crush you.
The boss can be speedkilled with the Brown weapon. Orange weapon's concentrated damage also gets a decent kill time while taking out debris. The Blue weapon, though piercing, doesn't deal enough damage to be useful, nor does it take out the debris effectively. Red isn't concentrated enough to punch through the gaps in its shield. This boss's debris appears to be potentially milkable for points, not sure if bosses actually time out in this game?
The Stage 6 boss relies on summoning rocks that it then fires at you in various ways. You can hide on the left side of the screen and just react to it as it attacks you. It's not so much about memorizing its attacks as it is just getting good at dodging them, or arriving with the right weapon. Even with a bad weapon you will eventually destroy it, but it's a lengthy fight if you accidentally went in here with the Teal weapon. The hard part is the section before the boss doesn't give any ideal weapons, so you need to carry Orange or Brown for a while before facing the boss, which both lack the sort of spread that can help in the stages.
STAGE 7:This entire stage is basically a waste processing facility. Red or Orange weapons are recommended early on, and you want Orange or Brown for the boss. There's lots of openings in the ceiling where junk falls onto a conveyor belt that you have to avoid, but note that the conveyor belt always sends the junk towards you so if you're to the left of the opening the junk travels left, and if you're to the right of the opening the junk will travel and fall to the right.
The second known collectable 1UP is found early on in a raised section that has two pits in a metal platform with mechs inside of them. The 1UP is in the second pit at the bottom right. Don't use Blue or Silver, they may be too slow to properly uncover it with shooting in time (I failed to get it once with Blue).
The first shield is extremely hard to get unless you know where it is and anticipate it. It appears at the top right of a section that immediately switches from scrolling right to scrolling down - I find it easiest to get to the right-hand wall, and use a bomb while rushing upwards to get it. You can also ignore the shield and grab one later far more easily in the next relatively easy section.
The section before the boss is tricky as the mechs react by firing lasers aggressively when damaged. Use a bomb if necessary. Make sure you have the Orange weapon here so you're set for the boss. Brown also appears to be effective. Very important: in this section before the boss, there's another 1UP hiding immediately above one of the conveyor belts.
This boss is nasty. Do NOT get too close to it as it has several attacks to discourage you from doing so. It fires 5 way spreads from above and below while entrapping you in a long corridor where bouncing shots spring up and down between posts along the length of the corridor. Afterwards, it then transitions to laser walls that block your shots. These laser walls contract and move around in a way I find extremely difficult to react to, and I plan to bomb my way through it if I'm about to be hit. when damaged, it'll start launching homing mines at you in threes - I'm honestly not sure what to do about these if you've died and lost your gunpods, you may have to bomb since you pretty much need the gunpods to block them.
When severely damaged, the corridor that traps you explodes open, it gains an eyebeam it fires regularly, and it starts causing the room to shake, sending debris down you have to dodge.
In general, this is a very nasty fight, that I plan on having a full shield and at least 3 to 5 bombs ready for. Orange or Brown both will get somewhat speedy kill times, and you definitely don't want to get stuck with a weapon that takes a while here.
STAGE 8:This is a very nasty final stage. It starts off modestly, with big enemies that aren't too difficult but have so much health you can really only kill them by pointblanking with the Teal weapon or Brown weapon. I can't even get kills on these with Orange.
Later on you encounter a couple of those shielded enemies you met in Stage 6, though the blue weapon works well as they seem to have less health than normal? You'll also encounter a refight against the Stage 1 miniboss who has a few new tricks. Namely, the front of it is now invulnerable and springs forward to attack you, with only the rear section vulnerable to damage. The second time it opens up it extends far enough that it's easy to scoot in and pointblank the weakspot.
The nastiest parts of the stage is the section with the spiky enemies and the part before the final boss. The spiky enemy section is tough as usual, but there's also enemies that love to fly in from the edges of the screen throughout the level. Do NOT go near any of the edges of the screen unless you have memorized the level! Later on in the level you're rushed by swarms of brand new enemies all around. Some of them actually drop bombs, but there's too many enemies to safely kill, so the trick is to identify the ones that drop bombs, and use a bomb now and then to safely work your way through, getting hit as few times as possible. You will probably die once or twice here. I honestly don't know what weapon really works here, no matter what you use bombs appear to be necessary.
The last obstacle before the final boss is a a new enemy made up of parts from the final boss. Its weakpoint is the central pillar it drops down now and then, which its legs will attempt to block. I would recommend either hiding at the far left of the screen where it's easier to dodge, or if you have a bomb saved up, ignore it completely and hide at the top of the screen. If you don't destroy it, it will eventually wander off on its own, and all you need to worry about are the turrets that show up along the top of the screen that aren't super difficult. Then, as the chain holding the boss gets close, use a bomb to pass through it harmlessly.
The final 1UP item is in this level, on the bottom of the screen immediately before entering the boss chamber, right after all you pass all shootable hamburger items.
The final boss of the game is extremely nasty. Use Orange or Brown. Orange is better since it moves around a lot during the second phase, limiting Brown's use. Red weapon may also be decent here. You can get a TON of damage in up close safely by bombing as it sends debris at you. Note that there's ice cream cone items at the top and bottom right sides of the chamber for points.
The first phase launches several waves of debris at you which you'll need a good weapon to safely clear (or better yet, use bombs and take the time to pointblank the boss for massive damage in between waves). It then fires thin lasers straight forward, and then launches a massive set of destroyable orbs forward that fan out. They have a fair bit of health, and the gimmick is that the boss will fire shots at these orbs. When hit, the orb glows briefly, then launches the shot diagonally at another orb. It looks like when shots travel from orb to orb they alternate between going up or down. The second time it uses this attack is very nasty as it then launches a series of GIGANTIC laser beam shots that ricochet off the walls, and the blind spots for this attack are tricky to get to safely. During the first phase you can shoot the rotating equipment above and below the core to destroy them, with each piece of equipment dropping an extra bomb! You can also get hidden ice cream cones at the top and bottom of the arena for some points.
When damaged enough, the boss starts openly floating around and fires off these homing clusters that erratically move around as they chase you. They're not super fast, but you can't shoot them down, meaning you have to outrun them as the boss itself flies around the room, launching expanding spreads of orange bullets. This part can be super hard, so don't be afraid to use your bombs to just get in its face and try to speedkill it down. Note that the game loops if you do beat it, and you'll have an opportunity to refill whatever bombs you've used here.
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LOOP 2 AND BEYONDThe game appears to loop infinitely. I've gotten to loop 3, stage 7 on a single credit, and no secret bosses have triggered, so it appears that the game loops and increases enemy bullet speeds by a % in each loop. 1UP items reappear in the loop, and it looks like once you hit 2.5 million points you get another score 1UP every million points (which is a huge quantity for the game, like one score 1UP per loop sort of thing once you're in loop 2).
The bullet speed increases make a lot of parts much more difficult than in loop 1 and careful use of resources is needed to survive!
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Please note that this information is pretty much entirely obtained via personal experience with learning and playing the game. SideLine is a fantastic MS-DOS shmup that sadly went completely unknown for decades due to a limited release, and as a result there doesn't appear to be any detailed information on the game available elsewhere. I would appreciate it if anyone could point out any errors, or could contribute additional information, such as if further 1UP items are hidden elsewhere.