No Export for You: 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 port oppose having two separate CD-ROMs and fixed many of the compatibility issues on Windows XP.
Keep Circulating the Tapes: It's also virtually impossible to find any retail copies of DVD PC version of Biohazard 2 through any store in this day and age.
What Could Have Been: Resident Evil 1.5, the original version of RE2, which was scrapped due to the developers being unpleased with the way it was going, BUT... A fan-compiled, playable ISO image of Resident Evil 1.5 can be found online, if you know where to look It was similar to the game that would eventually be released, with the main differences being with the characters.
Leon's very first character design was of a shorter-haired, tougher-looking guy. He was changed for too closely resembling Chris Redfield.
The female main character was Elza Walker, a college student and motorcycle enthusiast who is returning home to Raccoon City on vacation. She would be retooled into Claire Redfield in order to have a greater plot tie with the first game.
Robert Kendo (known here 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 was simply a researcher, 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. Also it was optional to save one, all, or none of the secondary characters; see here for more details.
The Chimera and Eliminator BOWs (which would appear in future games) were to serve as enemies.
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 zombie anything else), including the infamous fat zombies that didn't show up in an official game until RE3.
There were several new types of enemies created for 1.5, including spider-human hybrids a la the Chimeras in the first game, mutated gorillas and their offspring, as well as offspring for the giant alligator in the sewers.
There exists concept art depicting Annette Birkin also having mutated into G like her husband, although this allegedly didn't progress any further beyond a preliminary idea; as William Birkin's role was mostly unchanged in the final game from that of 1.5, it's unknown what would've led to Annette's mutation or what Annette!G would've done post-metamorphosis.
Tofu was used during development to test the game's hit detection.