Creator's Oddball: As a Survival Horror game, this game differs from most other games directed by Hideki Kamiya, who actually find most horror games to be too scary and tends to direct more action heavy games.
Descended Creator: Katsutoshi Karatsuma, one of the developers for the game, also lent his voice to the Joke Character Tofu.
Tofu was used during development to test the game's hit detection.
A very early design for the RPD main hall featured a pair of staircases in the back leading up to the second floor, which were eventually replaced with a fire ladder. The remake restores this concept, albeit with a slightly altered design.
Dummied Out: The first encounter with the Licker was supposed to start with it dropping the head from the decapitated corpse in the hall. The staff changed their minds late in development, perhaps for fear of censorship, but decided to simply cut out the cue for this and leave the head stuck up on the ceiling. It's normally out of the the camera's view since the game was meant for a 4:3 picture ratio, but playing the game on an emulator with widescreen support reveals that the head is still present. After the first time going through the hallway where that happens, the head is gone.
Executive Meddling: Around the time that the game was being made, Capcom was also making Mega Man 8. Apparently, Sony demanded that Mega Man 8 needed to be in 3D. Capcom retaliated by threatening to not release Resident Evil 2 on the PlayStation, which got Sony to back off.
Keep Circulating the Tapes: It's virtually impossible to find any retail copies of PC-DVD version of Biohazard 2 through any store in this day and age.
Multi-Disc Work: RE2 was released on two discs. You'd use one of them to play as Leon and the other to play as Claire. (Yes, you have to switch between them between the A and B games.) This was due to the dev team running out of time to compresses the audio and chose to ship the game as two discs.
The PC-DVD version of Biohazard 2 by SourceNext was released only in Japan, which is unfortunate since the PC-DVD version of the game combines both Leon's and Claire's games into one similar to the Nintendo 64 and Nintendo GameCube ports instead of having two separate CD-ROMs and fixed many of the compatibility issues on Windows XP.
The version of RE2 available on the PlayStation Store as a PSOne Classic is the DualShock Edition, marking the first time Europe got the PSOneDualShock Edition. Because the game is a North American import, it requires a 60hz TV set up to display properly.
Troubled Production: This was Hideki Kamiya's first horror game and the first game he'd directed, so he went in without a specific vision and instead spent most of the time experimenting with different gameplay styles. The game got to about 70% completion, but final approval was denied because higher-ups felt the game's environments were rather dull, that the emphasis on action detracted from the horror, and that the characters were uninteresting. The release date was pushed back a year to address these issues, which Kamiya was actually relieved to hear, as he knew the project wasn't coming together how he'd hoped. Professional TV writer Noboru Sugimura was brought on to overhaul the story, and Elza Walker was made into Claire Redfield so they could establish a better connection to the first game. The police station was also overhauled to be more ornate, justifying the creepy settings and puzzles. The game's audio also took up more space than expected, but rather than delay the game again to compress the files, Capcom just released the game on two discs when they probably could've gotten it all to fit on one.
Resident Evil 1.5, the original version of RE2, was scrapped due to the developers being displeased with the way it was going. note ISO images of 1.5 can be found online, if you know where to look, and there's an ongoing fan project to fix 1.5's numerous bugs and add in extra content to make it into a fully playable game. While it's similar to the game that would eventually be released, it does contain some notable differences:
Leon's very first character design was of a shorter-haired, tougher-looking guy. He was changed because he resembled Chris Redfield a little too closely.
The main female character was Elza Walker, a college student and motorcycle enthusiast who returned home to Raccoon City on vacation. She would be retooled into Claire in order to have a greater plot tie with the first game. The remake includes a costume for Claire based on her Elza Walker incarnation as a Development Gag.
Robert Kendo, known in 1.5 as John, and Marvin Branagh were to play much larger roles in the game, acting as supporting characters for Elza and Leon, respectively. In addition, Ada Wong was simply a researcher, and Chief Irons was a sympathetic character rather than a villain.
There were going to be two different final bosses (Golgotha and Salem) that each respective character would fight near the end of the game, this idea didn't make very far into development however. Also, it was optional to save one, all, or none of the secondary characters; see here for more details. The idea of two different final bosses was revisited with the remake's 1st Run campaigns: Leon faces Mr. X's Super Tyrant form, while Claire fights G-Birkin's fourth form.
The police station was going to look much more modern in appearance and awash with Bad Blue Lighting, as well as having a few more varieties of zombie cop (at the expense of most varieties of zombie civilian), including the infamous fat zombies that didn't show up in a released game until RE3.
The zombies themselves had far fewer textures and polygons, and this would allow more of them to attack players at once. The final game ended up going the opposite direction, adding more graphics to the zombies at the cost of having fewer of them appear in one room at a time.
There were several new types of enemies created for 1.5, including spider-human hybrids, which would have been similar to the Chimeras from the first game, mutated gorillas and their offspring, as well as offspring for the giant alligator in the sewers and a giant mutated horse boss.
There were different types of armor that Leon and Elza could equip. Furthermore, they would show damage on their character models as they were attacked by zombies and other creatures. The cut shown damage feature makes a return in the remake.
There exists concept art depicting Annette also having mutated into a G being like William, although this allegedly didn't progress any further beyond a preliminary idea; as William Birkin's role was mostly unchanged in the final version from that of 1.5, it's unknown what would've led to Annette's mutation or what G-Annette would've done post-metamorphosis.
Unlike in the final version where Umbrella is still operating, the company had folded by the time 1.5 had begun since the surviving S.T.A.R.S. members were spared from the Cassandra Truth and were believed when they told everyone what happened at the Spencer Mansion.
The Spencer Mansion was considered as a location you could visit while escaping Raccoon City, with the idea that a monster survived the explosion and was living in the ruined lobby and dining hall. That scenario didn't get developed beyond concept art. However, according to a developer interview with RE3 director Kazuhiro Aoyama, the monster that lived in the Spencer Mansion ruins was essentially "recycled" into the Grave Digger boss.
When Angel Studios (now Rockstar San Diego) was first figuring out which PS1 game to port over to the N64, they had two options. One of the options was rejected because the developer didn't want to ruin the product on a cartridge based system, so Angel Studios had to go with RE2. What was the other game in question? Final Fantasy VII.
Similar to the first game, a port for the Sega Saturn was in production for about a year before Capcom decided the system wasn't capable of a solid port (and was just about dead anyway).
Years later, ports of the first two RE games were pitched to Capcom by Italian studio Raylight, only to be cancelled when Capcom "lost interest in the viability of Game Boy ports." A very short proof of concept demo for a Game Boy Advance version of 2 was created by the studio, the ROM image for which can be found online.
When 1.5 was tossed aside, Kamiya was nearly booted from the team as the majority of the team blamed him for how the game's development went. Shinji Mikami exercised his authority to veto their objections and allow Kamiya to remain in his position.
For Resident Evil 2 proper, Marvin had a different death when you first met him; it would play out much like the same as what would happen, but then Marvin would start begging Leon or Claire to shoot him in the head, before collapsing. The corpses in the room would then reanimate and start attacking, followed shortly by Marvin himself.
featured a pair of staircases in the back leading up to the second floor, which were eventually replaced with a fire ladder. The remake restores this concept, albeit with a slightly altered design.