As it is with most games, the first Phase is just an introduction to the game without a lot going on. This will give you a chance in becoming familiar with how slowly your cyborg moves (which is crucial in being able to dodge certain enemies and/or attacks, once you get used to how he moves) and shoots.
Starting at Corridor 1, at first the only thing you'll have to deal with are Shockers, which kind of look like a vector version of a cow skull located at the top center of the screen in an archway. These will attempt to shock you via sending a damaging bolt of energy down to the bottom of the screen at you. Your mist weapons cannot reach it, so there's no way to shoot these. Their bolts also fire at a random location, so there is no pattern to follow there; just keep on moving and don't back up after passing an archway with a Shocker on it. If you move back far enough after passing one, it could shock you again, so just keep on moving forward and take as little damage from them as possible (one unit of damage per Shocker is enough).
Firestars will be your next enemy, which, like the majority of adversaries you face in the game, falls into two categories, being either a limited or infinite enemy. As you should notice while moving throughout the game, the vertical lines along the Corridors and Galleries (the third Phase) or marks throughout the Trench and Skywalk (second and fourth Phases, respectively) aren't just for decoration, they also mark areas where traps can be set off. Firestars are limited, where only a few will come out, and that will be it; other traps are infinite, where they will constantly come out (like the Decapitators in the next Corridor) and you will either shoot them until the end of time, get killed by them, or if you advance far enough through the Phase (usually just to the next marker will do it) you will deactivate the trap and they will cease to come out at you.
When a Firestar appears, they will swoop at you in a circular motion, traveling either clockwise or counterclockwise. They will swoop once, then with the second swoop they will either bash into you or pass you if you move forward. Use the second swoop to move forward to dodge these (since you can't destroy them) if you are on the opposite side of a Corridor from them, i. e. if they appear at the left side of a Corridor, move to the right, wait for it to start to make its second approach, then move forward and you should be able to pass it without taking a hit to your shields.
Afterwards, Corridor 2 brings about a rather nasty enemy with the Decapitators, as making contact with one will end your game, no matter how much energy you could have left. Being an infinite enemy, they will continuously emerge from the end of the Corridor until either you are destroyed or you advance far enough down the Corridor until the trap is deactivated and they will stop appearing. These are a very formidable enemy, which constant fire and patience will dispel them. You will have to constantly shoot them until they are destroyed, then with the split second (more or less) from the time one is destroyed and the next one appears, move forward a little; with each time you move, you are closer to advancing to the next wall segment that will deactivate the trap. If you are afraid that you won't destroy a Decapitator in time for it to kill you, move back a little while you are firing, but make sure to move back forward when you can! The longer you take in deactivating this trap means the greater the chance one of these could spell your demise.
The hardest part in these Corridors are when you have to face them along with Firestars at once, which comes next. Practice and patience are the main things here, as it can be difficult to advance far enough to stop the Decapitator traps. Also remember that, due to having your hands full, at times you're probably going to have to take a hit from a Firestar, which is better than being hit by a Decapitator, which means instant death. And also remember that Firestars are limited and it won't be long where you'll just be dealing with Decapitators.
Once you enter the final fourth Corridor before encountering the first boss, it begins with Firestars instantly coming your way, so be on the alert for them. This is also the hardest Corridor of the entire Phase, as there are many Firestars and Decapitators in this one. Not much can be said here except that practice is the key to trying to make it through all the way in dealing with everything.
Eye of Fury boss
The first thing you will do here is pick up your special weapon of the Remote Grenades. Practice with how these work, which the fire button will launch them, then pressing the button again will detonate them.
On the way to the Eye, all that you will encounter is a Shocker, which you already know how to deal with those as it is (luck!), so just keep on going as per usual.
Once the Eye appears, unless you're a real whiz in firing diagonally, it's in your best bet to remain in the center and just fire upwards. The Eye will fire rays that, at times, will have a gap in the middle, so chances are you won't take that much damage. Just try to time the Grenades correctly so that the moment the Eye opens (it will open, attack for a few seconds, then close for a few seconds) you will hit it; shoot these off fast enough, and you could get up to three hits with every attack. Do this quickly enough (along with gaining experience in doing battle with the Eye as it is) and it shouldn't be too long before you'll send the Eye away.
Once the Eye is defeated, you will get a key code for the next Phase area. Like when there is nothing attacking you at any given moment, there is no time limit to write down the code before it disappears. It is a seven digit number, which each digit represents a corresponding controller button, i. e. if part of the code is 2331, that means in that sequence you press button 2, button 3 twice, then button 1 once, etc. if you want to skip to another Phase the next time you start up a game. These codes can be selected by pressing button 2 on the title screen, buttons 2 and 3 will cause the onscreen cursor to select which code you wish to enter, then pressing button 4 after entering the code will confirm it. If you miss or write down the keycode incorrectly, you can go here to look it up on the FURY web site. Just note that the last 50 produced carts are all one number (i. e. you press buttons 1, 2 or 3 seven times each for a certain Phase to be skipped to) if you got one of the later I, Cyborg re-releases.
(And as a side note, there is no dedicated pause feature in the game. However, like several other FURY games [such as Sectis and Continuum], if, at any point in the game where you are not currently being attacked, there is a pause there in cause you need to go tend to something. You can come back an hour later and your cyborg will still be waiting for you. So that's something to keep in mind during the majority of the game, even if you're at a boss stage, since, as long as you're not in attack range of the boss, you won't take any damage.)
Trench (Phase 2)
Flying Filth will be your first, infinite enemy, coming in from the sides at a diagonal. With every few wall segments you pass as you are walking along and not being attacked, you might want to hold down the fire button, then quickly use the appropriate side spray button (two or four) to get rid of them. Keep on walking forward in order to cancel out the trap.
Cycloptic Arachnoids start on Trench 2, which will jump off to the side, out of your firing range. As soon as they do, get underneath them; i. e. if they jump off to the left, move your cyborg to the left so they can't shoot at you; if you're in the middle of the screen they'll definitely get a shot off of you. Keep moving forward the entire time though, since if you stop moving forward one after the other will come out, since this is an infinite enemy. Once they jump to the middle of the screen, start shooting forward, but don't move forward any more. Move left and right while continually shooting forward and it might only take one unit of damage off your shields; if you fire with sideways bursts it will shoot you several times (for some reason). These also come out after dealing with Flying Filth, so be on the ready for whenever you finish those off.
The next adversary of the Warbirds debuts on Trench 3, flying high out of your mist range. Pick a far side of the Trench (lets say to the right) and be on the lookout for when they fire a beam; they could fire at just the opposite side and spare you, or the beam can switch sides. Be on the ready to try to move in the opposite direction when this happens to make your damage minimal. And with all enemies on this Phase, they are an infinite one, so keep on moving forward, or else Warbird after Warbird will appear until you navigate yourself down the Trench far enough to stop them from coming out.
Flying Filth will also make an annoying combination with Warbirds on this Trench, so you'll have to deal with both at the same time. Like how a drummer uses a different speed beat from their hi-hat or ride cymbals as opposed to their snare, try to keep a rhythm of going forward and shooting while dodging the beam from the Warbird, if possible. The main things to keep in mind is to keep moving and the Filth only needs one hit from your mist in order to be knocked away.
The Binary Orbs boss(es)
As per usual, get used to how your new weapon works before engaging the enemy, as firing will launch a Remote Hover-Grenade, pressing the same fire button again will initiate it into a hover mode, and pressing the button one final time will then detonate it.
First the Orbs will take up positions in the top corners of the screen – one at the top right and one at the top left corner – and start shooting diagonally at you. Safe points are slightly to the left and right at the center of the screen. Aim diagonally at an Orb and wait for the opposite one to fire; I. e. aim at the right one and wait for the one at the left to fire. Once it does, maneuver the cyborg to the point where you think it is in the line of fire of a Grenade and launch it. Press the fire button again to initiate hover mode. If your Grenade is lined up with it correctly, detonate it. If you try shooting a Grenade at an Orb as it fires on you you will receive damage.
One thing to keep in mind is the vector drift that can occur, as all Vectrexes are different (hence the calibration requirements for games such as Y*A*S*I and Vector Pilot). So getting a hit on an Orb might differ for you than it does with myself. For instance, a hit on an Orb will register for me when I hit it at the bottom or the middle; if I detonate a Grenade and hit the Orb on the top, it will do no damage. If for you the hits occur at the middle or top of an Orb, then keep in mind where the damage works for your setup and work with that.
After the Orbs have taken several hits, they will drop down to different positions. Things change a bit here, even though you will probably still be shooting diagonally, although there is now a safe spot in the center of the screen (since they're right overhead now, rather than in corners) where you won't get hit by anything (which can work as an aforementioned pause if you need it). Also, you'll be able to creep really close to a line of fire from one of the Orbs while firing on the other; i. e. creep really close (and slowly!) to the line of fire to the Orb on the right and fire up to the left Orb. Also, if you found yourself favoring shooting at one Orb from during the first line of attack (say the one on the right, like I usually do), then perform several hits on the other Orb to try to even them up. Because once you are down to one Orb, it is very difficult to shoot, and you don't want that Orb to take 10 hits before destroying it, lest it destroys you first. So try to even it up a bit there. Meanwhile, keep shooting diagonally until they change positions again.
The next time the Orbs move, you will be shooting straight up at them. Again, wait for one to fire, then launch a Grenade at the other one, as now they will be firing faster and you will definitely get hit if you try to shoot at the one that is currently firing at you. Again, if you found yourself favoring one Orb, keep sending multiple Grenades to the other one to try to even out the damage they receive, as once an Orb takes its 15th and final hit, it will disappear, and the last Orb will start moving quickly across the screen horizontally. This part takes severe hand/eye coordination and concentration, so try to launch a Grenade when the Orb is headed away from you, which that way you won’t be launching a Grenade, trying to initiate hover mode AND dodge its fire all at once. Here you’ll just have to launch a Grenade and try to make it hover at the right time, THEN detonate it the next time the Orb crosses its path.
Gallery (Phase 3)
Rings of Fire are the first ones up as an enemy here. Try to stay in the center for as long as possible for when they show up and just move left or right enough to try to dodge them, then move back towards the center and forward; if you get stuck to the left or right side of the screen, with as slow as your cyborg moves, it can be difficult to dodge the Rings without taking damage. Back up a little as well along with moving from side to side to avoid them if you have to, but don't back up too much to negate moving forward until you're past them, since they're an infinite enemy that will keep on appearing until you can get past the trap.
If you're having trouble with the rings of fire, stay in the center. Pull diagonally backward (left or right) as they appear. As long as you are heading backward they move at half speed and are much easier to dodge. Then once past, push forward to move on. They come in sets and you can time your retreats to get past them more easily.
Gallery 2 is when the Electrochasms make their first appearance, which can suck you in and cause the game to end with no matter how much shield strength you had left. All you have to do is shoot them to keep them at bay and move forward to get past them, as they are also an infinite force.
Alternate way to deal with Electrochasms is to pull back on the joystick as soon as they appear. A quick flick straight down and they should retreat.
Gallery 3 is where Rods appear, which, once you're familiar with dealing with Firestars, then you pretty much know how to deal with these, as they behave in the same manner. Unfortunately it's not long until they get combined with Electrochasms, although, again, you pretty much just use the same strategy as dealing with the earlier Firestars and Decapitators together: keep moving and shooting to keep the Electrochasms at bay while trying to keep track as to which direction the Firestars are going so you can get to the safe (opposite) side of the screen so you can duck underneath them. Gallery 4, meanwhile, combines Electrochasms with Rings of Fire, so just try using the same strategy for the most part: keep firing to keep back the Electrochasms while trying to maintain a rhythm of moving towards and to the left or right of the Rings.
There's not much to learn about your Omega Disk weapon, as all you'll do is throw it. As far as dealing with Vectoria though, she will fire a Rod-like weapon (although they don't swirl around, they just travel straight) at you. She will throw them from a side; when she does this, move to the opposite end of the Gallery, i. e. if she throws one from the left (/her right), move to the right to dodge it. Aim at her middle when it's your turn to attack. Learn when it is too late to try to throw a Disk at her: if you have to move over to get her into range to throw a Disk right when she's throwing her weapon, chances are you're going to get hit and take damage. If you're able to throw a Disk and are in the process of moving out of the way right as she's throwing her weapon then you should be safe. Repeat until she disintegrates into nothing.
Skywalk (Phase 4)
This Phase begins immediately with Falling Stars bearing down on you, so be alert for those. Just firing one burst of your mist will take care of them. These are an infinite weapon, so keep on walking until they stop coming.
PR 1572 Units are next, which you'll need to head towards them in order to reach them with your mist. Do this quickly enough while firing and they won't be able to get a shot off of you. Next they'll be combined with Falling Stars, which, depending on the situation, it's usually best to shoot Stars first, since they only take one hit, whereas the PRs take a little more firepower in order to be knocked out of commission. And keep on moving forward the entire time to deactivate their traps.
Prince Thunderhead boss
Do NOT miss catching your Cosmic Boomerang or else Thunderhead will finish you off if you let your Boomerang go. Dealing with him is tricky, but if you're able to get a rhythm on him he can be dealt with and sent away with practice.
First off is that you HAVE to keep moving, as it's best to alternate firing the Boomerang from one corner of his mouth to the other in order to score hits off of him, plus if you get caught in the middle when he is shooting you'll take damage from his rays. Another thing you HAVE to do is hold down the fire button, since that saves you the 1/10th of a second (or however much time it is) that is needed to score hits off of him; pressing the fire button over and over again is never enough to defeat him and beat the game.
EDIT of the above for clarity: Do not stay in the same spot. Position yourself just to the left or right of the center screen. Fire the boomerang straight upward so it hits either the left or right corner of his mouth. As soon as the boomerang leaves your hand, move to either side and return to collect it before the boomerang is lost. If you are holding down the fire button the boomerang will leave your hand again instantly. As soon as it does, move in the opposite direction as you just did (i.e. If you fired, then moved right then left to catch the boomerang, then on the next time move left then right.) You should start to get a rhythm and score some hits without being hit. It may take a few tries to discover the rhythm so prepare to fail a few times. Takes 50 hits to defeat.