The solution is based on the US version of the game. There may be divergences from the Spanish version.
First Part - The Cellar
Starting the game, we would assume that you are using Isaac. Assuming that you have only one bomb, absolutely avoid wasting it immediately: you will need it in the following moments. A second note: the construction of the various play areas is, for the most part, random - for this reason, we will provide relatively vague indications regarding the actual proceeding along the various rooms, preferring instead to concentrate on providing more detailed instructions regarding the fight against the various bosses at the end of the level.
However, from the initial room you will be able to see doors proceeding in one of four directions - immediately go through one of these doors and get ready to use your weapons for the first time. In the room that follows, you will be faced with rather easy enemies to eliminate - we recommend focusing on the floating heads and zombies first, then moving on to the less tenacious flying insects. In any case, the structure of this area shows you what will also be the structure of the subsequent levels, which will always contain: a treasure room, a shop, a room with a boss inside, and a secret room. Remember that, immediately after your entry, all the rooms will block and you will therefore have to kill the enemies inside them without delay.
So explore the level until you reach the treasure room; it will be associated with a gold crown (on the map) and a gold door (visible on the screen). Also to be used as a reference for future levels, it will always be the most important room and consequently you will always have to keep a key aside to open access to it. As far as the keys are concerned, they have 3 main uses - to open access to shops, golden chests and keystones. However, as you progress through the level, you will likely find yourself interacting with one of the mini-bosses; usually, it will be one of the "Seven Deadly Sins" - although they are not really lethal, it is best not to take them lightly during the early stages of the game. After dealing with one, we recommend that you retrieve as many healing items as possible in the surroundings, thus making your way quickly towards the boss room. Also in this case, it is not possible to provide precise indications regarding the boss, since he will be selected randomly from a large roster, which in most cases contains Gemini, Larry Jr, Duke of Flies, the Fallen (if / when The Fallen happens to you, we highly recommend reloading - it's too strong for your current power level).
So, refer to the section on bosses to understand how to deal with who will happen to you. After completing the first floor, we recommend using any remaining keys to go and unlock the shop and pick up some items that may seem useful to you.
Proceeding towards the second floor, you will find yourself exploring a quantity of rooms equal to 13. Their structure is generally similar to that seen for the first floor, however the size of the individual rooms and - consequently - the number of enemies will undoubtedly be more high. Always try to walk one room at a time: visiting two at the same time could turn out to be a big mistake, the accumulated amount of opponents could put you in serious difficulty. After passing the first 12 rooms, you will find yourself in front of the boss who in this case could be Monstro, Gemini, Duke of Flies or Larry Jr. Also in this case, refer to our "Boss" section for more precise information. Having defeated him, recover the treasure and make your way to the caves, the second section.
Second Part - The Caves
This is a considerably larger and more dangerous area than the Cellar, given the presence of a higher number of enemies, larger rooms and stronger bosses, as well as more complex objects to reach (i.e. that will require a greater number of keys). Having said that, the general structure of the level will not be strongly dissimilar from the previous one: keep going forward, killing the enemies and always keeping an eye on the treasures in the area; at this point, as well as purely "accumulating" objects, you can also easily think about spending them.
In case you start having hit points, we recommend stopping by a blood / money converting machine - get rid of some treasure to gain additional life points. As for the bosses, as mentioned above, it is not possible to uniquely identify which boss will be selected by the game engine - therefore refer to the appropriate section to obtain explanations.
Third Part - The Depths
A peculiar addition that characterizes the level "The Depths" is the large presence of statues capable of spitting blood at the player - do not waste time trying to destroy them! It is totally impossible. Instead, it is preferable to dodge the blood that is thrown towards you. In addition, locks associated with the doors will periodically appear, preventing access to the bonus-boxes. Generally speaking, we can also guarantee that the first boss of this part will be Loki or Monstro II - in the worst case, it will be one of the previous bosses, but at a higher difficulty level.
When you reach the last levels of The Depths, you will find yourself near the last shop and / or the last treasure room: we therefore encourage you to visit both places, compatibly with your priorities. In case you have some money to spend, it will also be good to use it in full, or almost. When preparing for the boss fight, make sure you have completed all the necessary pre-objectives. The second boss in this section will always be The Mom: take a look at the boss section to get some information about it, in this case it will be almost indispensable - The Mom is a really complex boss.
Fourth Part - The Womb
This area is characterized by the large presence of bosses of various kinds; it is an area that can be considered as a "bonus", where your focus will be strongly directed towards pure combat, rather than the exploration of the various environments to try to find precious objects and bonuses of various kinds. Then walk along the first floor in a linear fashion, until you locate the first boss - which will be Blastocyst or Scolex; in both cases, the difficulty will be less than the fight against Mom. However, refer to our section on bosses for more information. Proceeding therefore to the second floor, you will have to see it with a variant of Mom ... the Heart of Mom. Again, the reference to the section of the bosses is a must.
Having defeated it, you will be offered the golden chest: open it to get your reward; in addition, if you have a sufficient number of life points left (ie more than 10% of your total) you will be able to access the Devil's Room. Inside the Devil's Room there will be a trap door that leads to the very last level of the game - that is Sheol.
Part Five - Sheol
It is the true "secret" final zone; what characterizes it is the complete absence of save points, as well as shops where you can gorge your HP for a fee, as well as bonuses of various kinds. Generally speaking, you will be faced with various bosses and mini-bosses of above average power. The most important general advice we can offer is: always try to favor a strictly defensive approach as you proceed. The absence of save points, as well as the possibility of gorging your life-points, coincides with the need to take as few hits as possible. The final boss of this area (and, we can finally say, of the entire game) will always be Satan. After defeating him, you can finally enjoy the endgame scene!
BOSS - The Cellar
Below, we provide useful information to overcome the most complex test in the history of The Binding of Isaac, namely the bosses that will be scattered along the level. Let's start from the first level, that is La Cantina.
He is one of your "first" bosses. Despite this type of role, this is a potentially rather complex boss - especially if this is your first experience in the game. Despite its very weak attacks and its ease with which they can be dodged by you, the boss has considerable health points and an excellent defense, so your shots will not be able to damage them seriously - it will take some time to reset. the HP of him. The strategy that "pays" the most sees you moving in a circle around the enemy attacking him continuously, trying to move further only when you notice that he is actually about to execute an attack. By continuing to employ this strategy, you will surely defeat him - albeit not quickly.
Video - Announcement Trailer
This is one of the most common bosses in the game - and luckily for you, one of the simplest. Just keep far enough apart, killing Harry's underlings one at a time - usually, he will "create" 2 or 3 bodies at a time, of random size. By hitting him repeatedly, several "pieces" of the body will be lost and Larry will become progressively weaker, until his final death.
The Duke of Flies
Try to pay particular attention to the "flies" associated with the Duke: kill all those that will attack you directly, so as to also be able to thin out the mass of flies that populate the immediate surroundings of the Duke himself - they in fact prevent your blows. to reach it. Generally speaking, the Duke has a very low amount of life points; it will often be possible to kill it by throwing a simple bomb - the difficulty lies in finding a "hole" in its large fly-based defenses, but with a little patience you will certainly succeed.
Gemini is "composed" of two different bosses, separated from each other - but who will always fight you in conjunction. The more "older" Gemini - Gemini Sr. - will follow you around the room, charging you periodically - pay attention to the speed of his charge, truly remarkable! At the same time, the Gemini Jr. will spit blood at Gemini Sr., then build up "anger" in case he fails to hit you - and when he turns tremendously red in the face, he will rush towards you to try and hit you.
In general, we recommend focusing on one of the two opponents at a time - at least in attacks (unfortunately, they will often tend to attack you in conjunction, so it is very likely that you will take damage when defending). When one of them dies, pay attention to the shower of blood that will ensue - dodge it entirely to avoid the damage that would ensue.
Boss - The Caves
Below, the bosses you will meet during the second level.
Of all the bosses in the caves, Chub is probably the simplest. Despite the fair number of life points at his disposal, most of his shots can be dodged with ease, given his slowness. It essentially has two strikes: a charge, a strike that sees Chub "extend" fully and lunge violently towards you - as well as being an easily predictable move, as you will immediately notice when Chub attempts to "extend", it can be exploited to your advantage: when you dodge Chub he will be able to hit and kill other enemies, as well as cause mines to explode along the way, thereby damaging himself!
The second move available to Chub sees him actually "create" enemies from his butt - a minimum of one and a maximum of 3 will emerge. If possible, we recommend avoiding the fight: it is preferable to move continuously in a circle and continue. to focus on Chub, possibly pushing enemies back only when / if they get too close to your character.
This is a giant ball of meat; similar to Envy, she will periodically float across the room, throwing herself at the walls and bouncing off them. In general, Fistula cannot attack you directly: the only damage you will suffer will be a consequence of your collision with Fistula during one of his sudden movements and / or consequent rebounds. Precisely for this reason, a strongly offensive approach is always to be preferred. After you have dealt enough hits to Fistula, he will split into 4 further parts - keep hitting them as you did with the main enemy, thus causing them to further decompose into 2 further small parts. Warning: when you have eliminated these eight parts, each being will turn into a Charger that will explode upon contact with you, so try to move quickly in another direction.
Peep will use a move called "circle spray" quite frequently. It is a blow that can always reach all of Peep's immediate surroundings; as a result, dodging it will turn out to be nearly impossible. One of the ways around this problem is to always keep a decent distance from Peep - take advantage of the "natural" cover provided by the room to avoid attacks, while trying to hit him in the moments between one attack and the next. Once Peep has lost an eye (or even two), remember that the eyes have a "life of their own", so they are able to block your blows and inflict serious damage on you if you are in a transit area. of one of the eyes - dodging them must therefore be your number one priority.
One of the most complex bosses to face in the entire game. Most of the time, it will position itself exactly in the center of the room, starting to hit you with lightning flashes in your direction. Despite his complete immobility, Gurdy can perform a large amount of attacks - starting with Blood wave, a move that will see Gurdy curl up on himself and then throw himself up and out on either side of the screen, and then quickly shoot a sphere of blood towards you; difficult move to avoid, you will have to immediately turn your gaze to one of these two sides of the screen and notice where Gurdy will come out and then quickly project yourself upwards and dodge her blow. Gurdy is also capable of "creating" both flies and Pooters, as well as simple Boils. These enemies will mostly go ignored, they will only have to be attacked directly when / if they try to attack you.
Unfortunately, one of the main problems associated with Gurdy is the sheer amount of life points at his disposal. You must therefore on every occasion, if / when possible, ignore his subordinates and attack your opponent directly.
Boss - The Depths
Below, the bosses belonging to the level "The Depths".
This is a rather complex boss to locate: typically, it will appear from the fifth chapter onwards. Its standard representation is that of a small red elf floating along the play area, then attacking the various characters in an apparently random manner. In general, his attacks can be summarized as follows: the ability to teleport throughout the room, the ability to "fire" an attack in any direction towards you, as well as the ability to make a triple 4-directional attack . In general, however, Loki has a very low level of life points, a situation that you can use greatly to your advantage, thus preferring a strictly offensive approach to battle, which will allow you to get rid of Loki in 3-4 minutes.
To eliminate Monstro II in an easy way, you will have to place yourself in the area directly opposite to the one where the beast resides, waiting for him to go and prepare his fearsome "Blood Beam" shot - you will know that he is about to launch it from the presence of a smile on his mouth. . So, dodge him quickly, moving sideways suddenly and moving circularly until you reach his back, hitting him. Monstro II will turn around, trying to hit you with another Blood Beam - just repeat the procedure to damage them again. Then repeat the same procedure again, until his life points are reduced to zero.
This is one of the most complicated bosses in the game, but also essential to be able to unlock its final part. The fight with Mom will always start with her attempting to crush you by slamming her foot to the ground. Avoid this attempt to move on to the second part of the fight. So, the real challenge will start: Mom has 4 different body parts that will appear in the area randomly. Her foot is able to perform a brief "heat search" to locate your position, then launch towards the ground and destroy all the rocks nearby (but, good thing, your opponents too!). Her eye, which will come out of one of the doors, also periodically, is completely defenseless: attack it repeatedly to inflict free damage on Mom, without risking anything.
The Mother's flesh is as defenseless as the eye, but it is able to "create" enemies to defend itself - in general, we recommend hitting the flesh repeatedly as long as it is exposed, then changing target (aiming at the enemies "emitted" by the flesh) as soon as you get the chance. In general, your approach to the battle with Mom will have to be strongly offensive, it is the only approach that can provide you with a good chance of victory.
This is a real replica of Monstro II: the only real difference is its ability to "emit" several Mini Gish, which can annoy you during the fight - we personally recommend ignoring them as much as possible (that is, until they are them to attack you directly), focusing on the main enemy.
Boss - The Womb
Below, the bosses belonging to the level "The Womb".
This is the weakest boss you will encounter while playing "The Binding of Isaac". He has a really low amount of HP - in some cases, he can be zeroed with even a single bomb and / or a particularly strong attack. However, there is a peculiarity: the tail is his weak point, hitting him in any other area of his body will have no effect. The general attack pattern sees Scolex jumping in and out of the room a number of times; after a while, he will move his head or tail outward and yell "Attack!" to try to hit you; therefore, he will dive again. The best time to attack him, as typical of these situations, coincides with the moments immediately following his attack attempt: you will have to move at speed towards one of the two sides, dodging the blow and going instead to hit his tail. By repeating this procedure, you will defeat him without any problems.
Significantly more complex boss than Scolex, at least in potential. It is an "Embryo" type enemy set in a kind of jelly ball. The opponent will periodically throw himself along the various sides of the playing area, shooting caustic blood-blood, which he will always try to avoid. Unfortunately, killing him once will not be enough to resolve the issue definitively: he will in fact break into 2 parts, which will still be able to shoot blood in four different directions around them. By hitting these four parts as well, two more will come out, firing only one "stream" of blood each.
By killing even these small parts, single embryos will be created, which - fortunately - cannot even move; you can limit yourself to killing them. To be able to successfully eliminate this opponent, the keystone is only one: try to kill the initial form of him as quickly as possible. Once this is done, he will no longer be able to strike diagonally; as a result, you will be able to dodge his shots with considerable ease, even though they are relatively slow shots. When you go to face the four small "versions" of the enemy, we recommend that you stay on "who goes there" for 2-3 minutes, in order to get an idea about the attack patterns of the opponents and therefore position yourself near the only area where you will not suffer any crossfire from enemies. Often and willingly, this area corresponds to the central part of the room - having localized it, we recommend staying there for as long as possible, reducing the opponents to mere embryos, which you can then easily crush to achieve victory.
Starting the battle, you will be able to see Mom's heart associated with two eyes, on its sides: destroy these first, it is necessary to avoid having particularly serious problems later. In general, Mom's Heart's behavior is relatively predictable: in the event that there are enemies associated with her (such as the aforementioned eyes), her heart will rise to the outside of the screen, proceeding to hide. In case there are no enemies, the heart will proceed downhill and summon others. In practice, the only moments in which you can strike the heart with ease are the moments between the moment in which you kill her subordinates and the moment in which the heart will rise on her to "create" others. Try - in these moments - to accumulate as much damage as possible.
When his HP has been reduced to about 33% of the total, you will hear the Mother scream Isaac's name and - from here on out - the battle will become progressively more complex. In fact, the heart will no longer hide, it will instead remain in the small shaded area, periodically evoking various enemies that will appear around you. Despite the increase in complexity, your overall attack pattern will have to remain completely unchanged, that is - hit the opponent in moments when you are not committed to eliminating nearby enemies.
It is a 2.0 version of "Mom's Heart": in practice, it is identical but the difficulty is increased by its spawning of real bosses, instead of standard enemies. Clearly, therefore, it is an enemy that must be faced after you have acquired some experience - but the general type of appropriate attack remains the same, that is, you will have to hit It Lives! in the moments immediately following the elimination of his subordinates.
Boss - Sheol
Below, the bosses belonging to the level "The Womb".
As you can imagine, this is the final fight. The battle will be divided into three phases; before starting it, we strongly advise you to accumulate a certain amount of life-points. Also, in case you have a Bible, you need to use it before entering Satan's room - otherwise, you would be killed instantly.
During this first phase, Satan will go to summon the Fallen associated with two leeches capable of exploding. Focus on leeches initially, as they can cause a variety of damage to the Fallen if they "detonate" at the right moment - in practice, they can be used as a true equivalent to "bombs". For the rest, we ask you to refer to the section on Fallen, as the fight will unfold in exactly the same way.
Having eliminated Satan's assistants, the devil himself will decide to attack you. He will rise from his pedestal, transforming into a huge demon. His initial form will position itself adjacent to the back wall, then travel in both directions, periodically. The opponent will periodically "spit" two huge spheres of blood, which inflict 1 point of damage each, if / when they hit you.
Also pay attention to your periodic passage in front of Satan's face: in that case you could suffer a quick, lethal attack in which Satan will spit a stream of blood from his mouth and shoot two "rays" from his hands - we therefore advise not to pass in front of the face, since the attack will be carried out very quickly and therefore an almost inhuman reaction time is required. Trying to always remain faithful to this trick, as well as dodging the other spheres of blood, you will be able to reset his HP in a slow, methodical, but effective way.
Satan will fall to the ground after resetting his life total. Soon after, however, he will manage to jump out and start laughing hysterically. This behavior marks the arrival of the real final phase of the game. Satan, having a kind of raised support area, will try to crush you using his feet - in a similar way to what was seen in the battle against the Mother.
When your feet hit the ground, they will release a huge explosion around it. The legs will then descend into the area repeatedly, one after the other. While you are busy dodging all this good things, Satan will continually summon explosive leeches (up to 2 at a time), which can cause a variety of damage if you don't pay close attention. In general, your battle strategy can be summarized in the following way: you will have to try to avoid all these lethal blows from Satan and take advantage of all the moments of short "interruption" between one blow and another to inflict damage. The battle will go on for a very long time, but you will be able to eliminate the opponent with confidence, without having to make countless attempts.
Video - Trailer
Boss - Rider
Below, the bosses belonging to the "Rider" type - they can appear in any level (or almost), taking the place of other standard bosses.
This is the "Rider" that populates the caves. You will see him floating in the area aided by his horse, periodically evoking charges and "subordinates" around him. He will also leave a trace of slippery slime around him: beware, it is toxic and will damage you when / if you touch it! Its final attack consists of a sphere of slime thrown towards you, which explodes as soon as it comes into contact with the ground, leaving more slime in the area - as soon as you see the sphere appear near the enemy's head, wait a second to understand the trajectory towards which it is launched, then move sideways at maximum speed to dodge it.
In general, the best way to deal with it is to ignore the enemies it creates, instead paying more attention to the traces of slime left on the ground - as well as its fearsome grenades: in fact, if you are hit in full by one of these grenades , you will be further restrained in your progress by the presence of the slime attached to your limbs. Having avoided these two hits, you will be able to focus all your attention on the enemy, thus being able to eliminate him in speed - you will certainly take damage from his subordinates, but it is still damage.
This is the "Rider" that you will find in "The Depths" level. In general, his attacks can be identified in the following: he is able to fire circularly spheres of blood capable of moving at remarkable speed; he is also able to fly through the air by exiting the screen, then releasing six troll bombs across the entire room. You can also provoke it in such a way that it makes a charge: in this case, it will first attack horizontally up to the middle of the room, then it will stoop and come back attacking again horizontally along the remaining part of the room, to finally return to its initial position ( having understood the pattern, you can jump and duck adequately to avoid hits).
After taking a sufficient amount of damage, War will lose his horse - in this condition he will be tremendously vulnerable, so we strongly recommend that you maximize your attacking skills to be able to pulverize him completely.
This is the latest opponent in the Rider series. He will appear near the fourth chapter, The Womb. He is able to summon Scythes to attack you from the opposite side of the room - often in pairs, other times in quartets that will travel the entire room. Death is also able to "fire" a kind of hourglass, which is able to slow down both you and your attacks. When you have managed to reduce his life points by 50%, Death will proceed to summon pairs of knights - rather annoying, we recommend continuing to focus on the main enemy, the only real way not to waste time unnecessarily.
In general, the combat strategy that works best sees you always trying to dodge Scythes, focusing your attacks only on those that are actively bothering you, as well as - more than any other - on Death himself. Having then reduced it to its "final" form, the general strategy will remain the same, but you will have to further pay attention to the horse which will periodically attempt to charge you. It too can be ignored until you have finished Death itself, so you will be able to fight it at a later time, with greater tranquility.
The Headless Horseman
This is a special boss, similar to the Fallen it can replace any Rider. His form is actually that of a headless horseman: his body behaves similarly to the second "form" of Pestilence, sprouting balls of blood that leave pools of blood in the area. On the contrary, his head will float in the air, periodically firing a kind of "fan" made up of three spheres of blood; on some occasions, he will also perform an easily dodged triple charge, at least the first two "phases" of the charge are.
Ultimately, we recommend eliminating the body first; the best time to attack it are the instants in which the head is busy charging repeatedly, you will in fact be indirectly forced to follow the body, but in this way you will dodge the attacks of the head without realizing it.
This is a so-called "Dark Angel"; the main problem with this character is the possibility of him appearing in one of the basement floors - similar to the "Headless Horseman". Taking you by surprise during the initial moments of the game, the subject could create really insurmountable problems. His general attack pattern sees him "fly" around the room and then spit out periodic spheres of blood. Occasionally, the Fallen will interrupt its continuous fire, instead going to "charge" you in a similar way to what Gemini did: you will still notice a slowdown in its moves right at the moment of its preparation, so you can dodge the blows by moving sideways at speed.
When his life points have reached 50%, he will split into two smaller autonomous versions, which will behave identically to the larger version - we recommend that you continuously move in circles in these situations, only in this way you can avoid the cross focus of the two subjects.
This subject will periodically appear inside the Devil's Room, often replacing Satan. In general, his defense and attack patterns are similar to "The Fallen", however there are some clear differences: he will shoot an extra blood ball for each attack, never try to chase you, and won't spit in reaction. at your stroke.
Unfortunately, there is a greater difficulty in defending yourself from Krampus's blows than you are used to with Fallen: Krampus is in fact easily able to hit you as you move in a circle; Nonetheless, moving in circles undoubtedly remains the most effective strategy, but you will have to periodically jump to dodge his blood-based rays. As far as the attack strategy is concerned, the watchword is "caution": always think first of defending yourself, only secondly of attacking; it will take a little longer, but it will be worth it.