Resident Evil 0

Overview

Resident Evil 0 was released exclusively for the Nintendo GameCube on November 12th, 2002 and is the 5th game in the series in terms of release date (counting the remake of the original to be a separate game) but is chronologically the first game in the series. It is also one of the last games in the main series to use the original control scheme & design, with Outbreak - File #2 being the very last.

It uses a team mechanic in which the player can control two characters in order to solve puzzles and defeat foes. A Nintendo Wii version of the game was released in 2009 and features minimal changes, the main change being that the game can be controlled with the Wiimote. It was originally slated to come out for the Nintendo 64 and up until 2016 was a Nintendo exclusive, before it was remastered for Sony and Microsoft consoles, and the PC.

In October 2018, Capcom announced a Nintendo Switch version of the game for release sometime in 2019.

Gameplay

Overview & Controls

Resident Evil Zero plays much like every other Resident Evil game pre-Resident Evil 4, mixing in third-person combat, exploration, and puzzles. Though like most survival horror titles, Resident Evil limits the player character's capabilities beyond the norm and ammunition for their firearms is generally scarce, intended to force players to use their supplies wisely and to choose flight rather than fight when possible. There are three different difficulty modes available: Easy, Normal, and Hard, with each one featuring tougher enemies and less ammunition to be found than the last.

By default Zero utilises the notorious 'tank controls' as players move via a third-person perspective throughout a number of pre-determined camera angles. Characters also cannot move and fire their weapons at the same time, and instead the character will 'perch' themselves to the ground when aiming. And while the camera angle perspective sometimes tends to purposely obfuscate the player's view of monsters, characters will at least (by default) aim their weapon at the closest enemy when players draw their gun. Simultaneously hitting down and the 'run' button will have the player character do a 180 degree turn, as is custom with Resident Evil games since Resident Evil 3: Nemesis.

The story is largely portrayed via in-game cutscenes, however there are also a number of Files (diaries, memos ect.) players can collect. These will often provide additional insight into the goings on across the overall narrative, but some are more vital as they will provide information pertaining to solving puzzles or maybe hinting as to where to go next.

Cooperative Functions

Zero's one primary component that separates it from previous games of the series is its two-protagonist setup--being Rebecca Chambers & Billy Coen--each of whom can be controlled by the player. When controlling one the other will follow closely by default and will attack any encroaching enemies - though it will use up any ammo it has access to in the process. It will also fire alongside the player at whatever enemy they're targeted at, though its frequency of attack is rather slow. Such behaviour related to its attacking and following procedures can be turned off, so it will merely follow the player without engaging in combat and/or will wait on the spot. When travelling together the player can control the movement of the alternate character as well with the c-stick/right analogue stick (default GameCube/PlayStation & Xbox controls), though the secondary character will only run via this method and cannot walk.

Rather than having both characters following one another, players can also split them up. When split up the secondary character will await in the area they're left in until the player takes control, though they're still vulnerable to attack should there be any nearby enemies. If the secondary character is being attacked then the player will receive a warning over their radio; if players don't switch to the alternate character to save them, there's a high chance they may perish. This function is forced upon the player so as to solve certain puzzles, such as by having one character access an area that only he/she can travel to, while the other sends key items and/or supplies via a dumbwaiter.

While the majority of the game plays out with these mechanics in play, there are two occasions where the characters are separated without the ability to switch between the two for the sake of the story. One sequence forces players to play as Billy, while another, much longer segment has players play as Rebecca on her own.

Playable Characters

Both Rebecca and Billy each have their own strengths and weaknesses to help distinguish the two. Due to his experience in the marines, Billy is significantly more durable than Rebecca and can withstand more damage before dying. His strength also allows him to interact with certain objects that Rebecca cannot, though the opposite is also true for Rebecca who can access certain areas that Billy cannot due to her smaller size.

Though Rebecca can't withstand nearly as much punishment as Billy, she is the only one of the two who can mix herbs, making Billy quite literally the only playable characters in the series who cannot mix herbs together. Her medicine case that she uses to mix herbs is also used for mixing certain chemicals to solve puzzles.

All weapons in the game can be used by both characters largely to the same effect.

Inventory

The inventory system for Zero received a slight overhaul from previous games. Each of the two characters has their own six-slot inventory, to which they can trade items between each other at will so long as they're in the same room. However there are no item boxes to be found in the game. Instead players can opt to drop items onto the ground, to which will persist there until/if it is collected. Any dropped items will also show up on the map.

Each character has their own personal item that's housed in a separate inventory slot - no other items can be exchanged into this slot. Rebecca has her medicine case, while Billy has a lighter.

All items and weapons can be examined by the player, allowing them to get a closer look and turn the object around. This can sometimes change the properties of certain key items, such as unlocking/opening a key item to reveal another inside, or may at least change the title to reflect the item's true identity.

Most items and weapons take up a single inventory slot, however there are a select few that require two to carry. These are:

• Hunting Gun
• Shotgun
• Grenade Launcher
• Hookshot
• Rocket Launcher

Health & Herbs/First Aid Sprays

A character's health can be seen via the inventory menu, with an Electrocardiograph Machine showing a character's status. The different statuses are:

• Fine - The character is in good health.
• Caution - The character is roughly at half health.
• Danger - The character is approaching death.
• Poison - The character is poisoned and their health will slowly deplete.

Besides the EKG, players may also note the character's stance. Whence the characters starts holding onto their hip, that is a sign that their health is at least in the Caution state, or may even be poisoned.

Carrying the tradition set by the original Resident Evil, characters use a small variety of herbs to heal themselves and cure poisons. Though as mentioned before only Rebecca can mix herbs. First Aid Sprays are also available, though they only have the singular purpose of healing the character fully. There exist three herb types, all of which can be combined in some way for different degrees of healing:

• Green Herb - On its own will restore 25% of health.
• Blue Herb - On its own will cure poison, though will not restore any health.
• Red Herb - On its own does nothing.
• Green + Green Herb - Mixed will heal the character by roughly 50% of health.
• Green + Green + Green Herb - Mixed will heal the character completely, though not of any poisons.
• Green + Blue Herb - Mixed will heal the character 25% of health and cure any poison.
• Green + Green + Blue Herb - Mixed will heal the character 50% of health and cure any poison.
• Green + Red Herb - Mixed will heal the character completely, though not of any poisons.
• Green + Red + Blue Herb - Mixed will heal the character completely including poisons.
• Red + Blue Herb - Mixed will do nothing.

Saving

Like every other main Resident Evil game pre-Resident Evil 4, Resident Evil Zero requires that players find one of the many typewriters located throughout the environments to save, and must also have at least one ink ribbon item in their character's inventory. However whereas Save Rooms would always be devoid of enemies in previous games, this isn't the case for Zero.

Story

Main Characters

Rebecca Chambers

The youngest member of STARS at only eighteen and one of two protagonists, Rebecca serves as the medic for Bravo team. However despite specializing in more of a supportive position, the events of Zero will force her to take on that of a much more combatative role than she could ever have predicted in order to survive.

In spite of her young age Rebecca is shown to be a capable officer, and is much more mature and independent than her age may suggest.

Billy Coen

Fellow protagonist to Rebecca, Billy is an ex-marine who was sent for execution due to allegedly killing twenty three people. Though while he at first portrays himself as standoffish and antagonistic, with him literally introducing himself to Rebecca down the barrel of his pistol, the two quickly grow to depend on one another. That it is Billy that suggests they team up to better their chances in surviving the hordes is the first of many hints that he may not be quite the monster his criminal record implies.

As the game progresses, Billy is shown to exhibit a quiet sensitivity about him. And while he may still be the more physically imposing of the two, he all the while proves to be a far cry from the 'alpha male marine' that he is first put forward as.

Enrico Marini

The stern but well respected captain of STARS Bravo team. While Marini only plays a small role in Resident Evil, in Zero he is allowed much more screentime. Despite all of the zombies and monsters the team are forced to defend against, Enrico will recurrently appear to remind Rebecca to keep an eye out for Billy Coen, while Rebecca hides the fact that she is working alongside him.

Albert Wesker

The Alpha team captain and overall commander of STARS. By this point Wesker is still unbeknownst to his comrades a double agent working for Umbrella, the very company that inadvertently instigated the events of Resident Evil Zero and Resident Evil. As such, Wesker's role is kept at a distance, as he (along with William Birkin) monitors the two protagonists from afar via CCTV while he also attempts to uncover what caused the T-Virus leak on the Ecliptic Express.

• Voiced by Richard Waugh.

Plot

Resident Evil 0 takes place on July 23rd, 1998. The S.T.A.R.S. Bravo team is dispatched to the Arklay Mountains to investigate and find the cause of the murders that have recently occurred. While over the forest the Bravo team's helicopter is mysteriously forced to crash land. Upon leaving the crash site, the Bravo team discovers an overturned Military Police vehicle, as well as orders for the transport of a prisoner to be executed.

Rookie team medic Rebecca Chambers discovers the Ecliptic Express stopped and without power in the middle of the forest. Upon entering the train, Rebecca encounters numerous zombies, and infected canine. Pressing further throughout the train, Rebecca meet Billy Coen, the prisoner that was being transported to his execution. With little control over the recent events, Rebecca reluctantly agrees to team up with Billy, to get to safer ground, still vowing to bring him into custody if they both make it out alive. Further exploring Billy and Rebecca meet what appears to be a possible survivor, but before getting too close they find out it is a humanoid leech. Billy disposes of the leech creature, afterwords they see a lone man outside of the train standing on a cliff who appears to have some sort of control over the leeches. Unable to identify the mysterious individual, they must find a way to restore power to the train and get out of the forest. Once, power is finally returned to the locomotive, the train speeds to an unknown destination and eventually derails.

Seemingly unscathed from the train crash Rebecca and Billy end up at the trains destination. The mansion like building, is actually revealed to be a training facility for new employees of the Umbrella Corporation, and upon entering they are welcomed with a pre-recorded message from the head of the facility, James Marcus. During their trek through the training facility the pair is face with numerous zombies as well as plenty of new abominations. Over the course of their time together, Rebecca begins to see that Billy isn't a quite the criminal type, and begins to wonder why he was sentenced to be executed. The two eventually discover an underground portion of the training facility and are separated when the floor that Rebecca is standing on collapses. After being rescued by Billy, she questions him about what he did to get the sentence he had been handed. Billy finally explains, that he was part of the USMC (United States Marine Corps) and during a mission in Africa, his commanding officer ordered them to exterminate civilians of an African village that was suffering from a civil war. Billy refused to follow the orders, and once the information proved to be false, the slaughter was blamed entirely on him.

Upon entering an abandoned sewage treatment plant, the duo encounter James Marcus. Marcus, had been monitoring Coen and Chamber's progress throughout the training facility as well as the other areas they visited. Marcus reveals that a decade ago Lord Ozwell E. Spencer has Marcus assassinated, in the midst of the research on his leech research. He explains that the Queen leech from his experiments crawled into his mouth after he was shot, and the T-Virus that the leech was injected with was able to resurrect Marcus. Midway through his speech, the Queen leech takes over Marcus' body, and causes him to mutate into a new type of leech monstrosity. After toppling the Queen leech, Rebecca and Billy escape the training facility just as it is rocked by a gigantic explosion. After the escape, Rebecca takes Billy's dog tags as "proof" that he didn't survive the incident, and then the pair amicably part ways. In the distance Rebecca is able to see the Spencer mansion.

Weapons

Knife

Considered to be a last resort tactic, the knife does very little damage and has dangerously small reach. Because of its low effectiveness, it is usually best for the player to just run or attempt to avoid the enemy rather than combat it. Billy comes with a knife equipped, while Rebecca does not. Although there's another knife that can be found in the game. Rebecca and Billy have a different animation set for using the knife, however the effectiveness is largely identical all the same.

Samurai Edge

Rebecca's own custom STARS-branded handgun. While the Samurai Edge is generally regarded as a rather efficient weapon in the series, in Zero at least Rebecca's pistol is about on par with the handguns of the previous games and doesn't hold any special properties. Its fire rate is slower than previous iterations of the weapon and its overall damage output is moderate at best. As with all handguns it's most suitable for the lesser enemies of the game, such as zombies in particular.

It can eventually be fitted with a scope that introduces the chance for it to score a critical hit.

Handgun

Billy's own military handgun that he stole from the military police that were escorting him to his execution. Its fire rate is the same as the Samurai Edge, although it's slightly more powerful and has a chance to score a critical hit from the outset.

A scope can be fitted to Billy's handgun as well, which further increases its chances of a critical hit and also provides a boost to its fire rate.

Hunting Gun

The first available shotgun of the game. Unlike most Resident Evil shotguns, however, this one can only hold up to two shells at a time. It is a powerful weapon all the same and is vital for beating the Scorpion on the train.

As with all RE shotguns it can be used to completely destroy a zombie's head or legs, should the player aim up/down respectively when one is close enough.

Shotgun

An alternative to the Hunting Gun. Once this has been found the Hunting Gun is then made to be virtually redundant due to this weapon's much larger ammo count.

Grenade Launcher

As versatile as ever, the Grenade Launcher is a powerful weapon that is ideal for boss battles, and can equip a small variety of grenade types. There are the regular explosive grenade rounds, which do a sizeable amount of damage against just about anything; flame rounds, which while powerful, are especially effective against insect & arachnid monsters as well the leech zombies; and acid, which is the most powerful grenade type but also the rarest to acquire.

Magnum

The requisite magnum for Zero is a 50. caliber magnum pistol, which most resembles the desert eagle. It is the most powerful weapon in the game, with it being able to kill nearly all common enemies with a single shot, and is a great contender for boss fights. Its one drawback is ammunition is extremely scarce.

When wielded by Rebecca the weapon undergoes a decrease in its firing rate due to Rebecca's inability to handle the recoil. However Billy can more efficiently withstand the recoil and can thusly fire it faster.

Molotov Cocktail

The game's one and only throwing weapon. Molotovs are primarily useful for fending off the leech zombies, however it has a noticeable animation windup whence thrown and can be difficult to accurately throw it to where the player wants. While molotovs can sometimes be found as is, they more commonly require the player to build them themselves by combining an empty bottle with a gas tank.

Enemies

Zombies

The staple of the older Resident Evil games, zombies are as prominent as ever in Resident Evil Zero. Slow and sluggish in movement, but dangerous up close, zombies are durable enough against gunfire that they can prove to be extremely dangerous even just in small numbers, especially due to the typically claustrophobic environments. When encountered on their own, however, zombies can be dispatched relatively easy so long as the player has enough ammunition to spare. As per usual, zombies are best dealt with the pistol or sometimes the shotgun, which can kill a zombie with a single shot if the player aims directly at its head once close enough, or can at least reduce the zombie to a literal crawl by destroying its legs.

Zombies attack by grabbing and biting the player when close, but will also puke out acid instead if they can't quite reach the player. Some zombies will be encountered lying on the ground, seemingly pretending to be dead, and will grab at a character's leg should the player get close enough. However, the leg bite does little damage and will always result in the character killing the zombie with a single stomp or kick.

Cerberus Dogs

Alongside regular zombies, some sort of iteration surrounding infected dogs have persisted across nearly every Resident Evil game to date. Starting at the beginning, so to speak, the Cerberus Dogs of Resident Evil Zero are infected Doberman breeds, purposely engineered to be a form of B.O.W. Cerberus dogs retain the same agility and tenacity as a regular dog, though with a massive increase in aggressiveness, brutality, and stamina.

Like zombies, Cerberus dogs are best left for lesser weaponry like the pistols and shotguns. Running past is always an option as well, as both Rebecca and Billy are just ever so slightly faster than the canines. However their attacks can sometimes cover just enough distance to close the gap and catch the player character.

Unlike other games in the series, there are only four dogs the player will encounter throughout the game, all of which are located in the beginning Ecliptic Express section.

Crows

As always, crows prove to be more of a nuisance than a genuine threat. They do minimal damage and can often be killed with a single bullet; their numbers are always many, however. Sometimes a shotgun blast might be worth it to take a pack down, but otherwise they're best just ignored.

They only have one attack by way of pecking at the player, which while does little damage will keep the player stuck in a short animation of trying to wave them off.

Bats

Somewhat similar to crows, bats also function more so to harass than pose any serious threat. In fact bats are even less threatening than the crows as their attacks don't force the player into a prolonged animation of waving them away.

These are only encountered during the Giant Bat boss battle.

Leechs

Another minor enemy, most prominently featured in the beginning train section. Leechs pose little threat overall and can be killed merely by the character walking over them. Though should they latch on to the player, they'll have to wait through an animation showing the character shoving them off.

Web Spinner

Giant, hairy spiders, the Web Spinners of Resident Evil 0 appear only briefly within the underground levels of the Training Facility. Always encountered in groups, they can crawl along walls like any other spider, and will often try to charge forward and bite players when given the opportunity. However, their greatest weapon is their poison spit, which they will routinely spray; it has a fairly long reach of attack and has a high chance of poisoning the player, though the base damage it inflicts isn't quite as alarming.

Web Spinners have surprisingly tough hides and are most susceptible to the Grenade Launcher - specifically when equipped with flame rounds. They will also often strafe once they've been shot and attempt to counter the player as such. If a Web Spinner is killed with its sack intact, a large multitude of baby spiders will seep out of the corpse and attack the player. Though their damage is even less than that of a crow and should the player leave the area, they will return to find them all gone.

Eliminator

Eliminators are an infected breed of monkeys that are exceptionally fast and agile, somewhat akin to Hunters. However they are also rather small to boot, so should they happen to get close enough the player must then aim downwards to get a shot. Their main two attacks are to rapidly slash at the player when close, and to leap through the air and slash from afar. They are still vulnerable amidst their leaping animation, however, providing the player with an opportunity to show them down if they can react fast enough. Eliminators are rarely encountered alone, and if a group of two to three swarms the player they can prove to be highly difficult to escape without taking damage.

Despite their small size they're still rather sturdy. The handgun is outright useless--that is besides to potentially finish them off after already being weakened--as they shrug the bullets off completely and will continue their advance. As such the shotgun and grenade launcher are the most suitable.

Hunter Alpha

The green Alpha variant of the Hunter makes another reprisal to the series, though they're not quite as prominent as they are in the original Resident Evil and its remake. They operate identically to how they do in the remake, and attack similarly to the Eliminators. They will attack with broad slashes when close, but can also perform a mid air leap to attack and also close the distance - like the Eliminators also they can be shot out of the air during their leaping animation.

They're rather durable as well, more so than the Eliminators, making the shotgun or grenade launcher, if not the magnum--which can kill them in one shot--the most appropriate weapons for use.

Plague Crawler

Lurker

Marcus Mimic / Leech Zombie

A zombie-like enemy comprised of dozens of leechs. They will usually be of the appearance of James Marcus before then being shown to vibrate and revealing their true appearance. The few seconds it takes for it to transform can provide the player with the opportunity to quickly rush past it.

Leech zombies are perhaps the most difficult enemy in the game, as their movement speed is fast enough to catch up to the player, their regular attacks can be stretched out to attack from afar, and their close-range bites deal much more damage than that of a regular zombie.

They are also highly resistant to most forms of damage - that is besides fire, which will make quick work of them should players have any molotovs or flame rounds for the grenade launcher. If killed by any other means beyond fire, then the leech zombie will explode, dealing a great amount of damage if its radius reaches the characters. It will at least begin to convulse and expand as a warning to players that it's about to explode.

Whenever a leech mimic appears it will be accompanied by a unique musical theme.

Boss Battles

Stinger

Centurion

Giant Bat

Proto-Tyrant / T-001

Queen Leech Part I

Queen Leech Part II

Unlockables

Costumes

A single completion of the game will award players with some new costumes. Billy gains one, being an Italian suit w/ shades, while Rebecca gains two. One is a cowgirl outfit, to which she also wears in the Resident Evil remake should Chris happen to be wearing an alternate outfit, and the other is an outfit comprised of a leather tube top and pants.

Leech Hunter

Much like previous instalments in the series, Resident Evil Zero features its own unlockable minigame. The concept is that Billy and Rebecca must collect a certain amount of color-coded, leech-themed jewellery pieces before exiting out the Umbrella Research Facility front door. When collecting leeches it can only be done specifically for each character, blue for Billy and green for Rebecca, but they cannot swap using the exchange system or pick up the opposite color for their team mate. The unlockable costumes as noted above are available to wear in Leech Hunter as well.

There are a number of unlockable rewards available for the main game, which are unlocked depending on how many leech pieces the player collects upon exiting the facility. If one of the character dies then the player's progress is forfeited. A list of the rewards is as such:

• 0-29 - Submachine gun ammo.
• 30-59 - Infinite handgun ammunition.
• 60-89 - Infinite Hunting Gun ammunition.
• 90-99 - Magnum Revolver is added for collection in Second Class Private Room B.
• 100 - Infinite ammunition for all weapons.

HD Remastered Port

Following the success of the Resident Evil remake remastering, a similar such remastering was announced for Resident Evil Zero on May 26th, 2015 for an early 2016 release. Though development began on Resident Evil Zero's remastering before even the remake remastering was released.

Like the remake it was released on PS3, Xbox 360, PS4, Xbox One, and PC. The port was handled by the original director of RE0, alongside many other members of the game's original development team.

As with the remake, it includes widescreen support as well an alternate control option alongside the classic tank controls.

Rebecca Chambers T-Shirt Contest

On July 10th, 2015 Capcom announced a contest for fans to upload t-shirt designs. Fans could vote for their favorite designs, with up to three winners, to which would then be released as downloadable costumes for Rebecca to wear in the game.

For voting towards t-shirt designs, fans would then be rewarded with early access to developer video diaries. These helped to explain certain aspects of the port's development and the work that was put into it.

Wesker Mode

Exclusive to the remastered version is a new mode called Wesker Mode, which is unlocked upon completing the game. In it Billy Coen is replaced by notorious series antagonist Albert Wesker, depicted in his Resident Evil 5 attire. Rebecca is still in tow as a fellow protagonist, now wearing a new, darker outfit as well as the same type of jewel that allowed Wesker to brainwash Jill Valentine into doing his bidding for him in Resident Evil 5. While D.C. Douglas returns to provide a few new lines of dialogue for telling Rebecca to follow or wait, all of the cutscenes instead simply feature Billy's dialogue coming out of Wesker.

Though mechanically speaking Wesker is more than just a simple character skin and has access to two unique abilities. First is a super-sprint, to which he can use to effortlessly rush past enemies, and the second is a kind of eye blast. The eye blast can be charged up for extra power, though even when at its lowest charge can make all of the zombies' heads within the vicinity explode. Rebecca does not gain any new abilities of her own, however, and neither character can change into any alternate outfits for this mode.

Wesker mode is played within the Normal setting.

DLC Costumes

RE0's Remastered version contains a number of new purchasable costumes for players to wear in the game. Two of which were given for free for preordering the game, while another two were awarded for preordering for Resident Evil: Origins Collection. All costumes can be bought together as a bundle, however this is the only means by which to purchase the preorder outfits, which aren't sold separately.

None of the new costumes are originally designed for RE0, and instead originate across a number of classic Capcom games and Resident Evil game ports. A list of the new costumes and their origins is as such:

Rebecca Chambers

STARS 1996

This is Rebecca's very original costume from the 1996 Resident Evil. Its one primary difference from her RE0 attire is that she wears a red bandana.

STARS 1997

This outfit originates from the 1997 Director's Cut release of the original Resident Evil. When selecting the game's Arranged Mode, Chris, Jill, and Rebecca are shown to wear alternate outfits to their regular RE attire, this being Rebecca's.

Sportswear

This outfit is perhaps Rebecca's most obscure, as she's only been shown to wear such an outfit in Resident Evil 2. Specifically in a secret photo players can find by examining Albert Wesker's desk in the STARS office fifty consecutive times.

Cheerleader

As with her 1997 STARS uniform, this outfit is first showcased in another of the original Resident Evil's many ports. Specifically Deadly Silence from 2006. Rebecca will wear this outfit should players select the alternate Ninja outfit for Chris once it's unlocked. The Ninja outfit, and by extension Rebecca's cheerleader outfit, can only be unlocked and worn in Rebirth Mode.

STARS Prototype

This is Rebecca's STARS uniform she wears in Resident Evil 0's prototype build, which was shown to run on the N64 console before being rebuilt for the GameCube. It shares many similarities with Jill Valentine's STARS uniform, most notably the addition of a beret.

Nurse

Rebecca's final DLC outfit is that of her unlockable Nurse costume from Mercenaries 3D. Which itself is a modified version of Sheva Alomar's DLC Fairy Tale outfit from Resident Evil 5.

Billy Coen

Wolf Force

This outfit dresses Billy up as one of the characters from Capcom's classic MERCS game on the Sega Genesis.

Cody

Billy's other DLC outfit continues Capcom's trend of having Capcom characters cosplay as other Capcom characters, with Billy dressing up as Cody Travers as seen in Street Fighter Alpha 3.

Development

Nintendo 64 Prototype

Resident Evil Zero was originally being developed for the generation before the GameCube - multiple platforms was planned, though the gameplay footage was shown advertised for the Nintendo 64. Development of Resident Evil Zero began in the Summer of 1998.

Much of what was developed for the prototype persists in the full retail release, such as the two-protagonist setup of Rebecca & Billy, it beginning on the Ecliptic Express train, and the death of Edward as he leaps through the window. Though there are certain features planned for the prototype that never made it into the full game; most notably is how one of the two protagonists could die, but the game wouldn't end unless both Rebecca & Billy perish. This idea was scrapped due to how Rebecca canonically dying would conflict against her appearance in the original Resident Evil. 'Running zombies' was another idea that was scrapped for RE0, though would pave the way for the design of the Crimson Heads in the Resident Evil remake.

During development for Zero's remastered release, Capcom released footage of RE0's prototype version to the public. It was shown to still be using the zombie moan fxs from Resident Evil 2, likely due to Resident Evil 2 being ported to the N64 years before. Billy's voice actor is also noted as the same one that would voice him in the full release.

Weirdly enough Rebecca is also shown to be wearing a beret, which is more so recognizable as the iconic hat of choice for Jill Valentine in her STARS uniform. There also exists concept art of Rebecca wearing a beret as well, despite the fact that she has never been depicted wearing such an item before in the series. Though it's possible that she was to lose the beret during the events of RE0. Nonetheless, she was once again designed to be beret-less for the full GameCube release.