BIOHAZARD 1.5 is the development name given to the first iteration of Resident Evil 2, which was scrapped in 1997. As the game was approaching its March 1997 release date, the developers were dissatisfied with the resulting product. Rather than releasing a game they were unhappy with, the developers took the risk of cancelling the game and developing the game again from scratch.
Leon S. Kennedy - Leon's role in the game was that of a rookie police officer defending the R.P.D.. Whilst on the roof, the infected enter. At some point he was to escape into the sewers with Ada and Marvin.
Elza Walker - Elza's role was as a college student returning to Raccoon City after a holiday. At some point, she joins up with John and Sherry where they plan their escape.
John - One of Elza's supporting character, known as "John" in 1.5. He is a civilian who seeks refuge in the RPD. He later became Robert Kendo in the final version of BH2.
Sherry Birkin - A supporting character for Elza, Sherry would be pursued by William throughout the game.
Ada Wong - Another of Leon's supporting characters, her name was originally "Linda" early in development of 1.5, but was eventually changed to Ada. Linda may have just been a "working" name for development purposes.
Brian Irons- Chief of the Raccoon City Police Department. Unlike in the final version, Irons was a supporting character who would aid in Leon's story. His office is a lot less morbid in 1.5.
Roy - Another R.P.D. officer, role and scenario unknown but it is assumed his role was similar to that of Marvin. Judging from available footage, it seems he somehow had connections with John. Roy also had the name of DJ at one point in production.
Crows and the Cerberuses share the same role as their Resident Evil 2 counterparts, with the dogs attacking the player in outside areas. Web Spinners were supposed to hide in ventilation tunnels before attacking nearby enemies. William Birkin was to be far more monstrous, able to kill other infected creatures. As evidenced by the little known footage available of the game, in 1.5 William would mention Sherry's name multiple times.
In the prototype, the zombies were significantly more gruesome, continuing to crawl towards the player with their body below the waist severed (it's possible for this to occur in Resident Evil 2, however enemies can only be blasted in half with the Shotgun and it's harder to pull off). In addition, the Zombies could climb on ledges and get up from crawling, which isn't featured in the final version. The various types of zombies were far more varied, including fat zombies, and multiple female zombies.
An Alligator and small crocodiles were also featured in the huge tunnel area in the sewers, where a fight presumably took place.
Two notable enemies in this version which never made it into the final version were a human/spider hybrid and infected baboons.
The Raccoon City Police Department was originally conceived with a more modern look; in the release version, it was changed to being an old building re-furbished by the police as a headquarters. To find examples of older buildings, the team snuck into a mansion in Japan to take photographs, deciding that it would be easier than flying to the United States and back.
1.5 is said to have had a wide range of weapons at Leon and Elza's disposal. The Remington 870 could be used by both Leon and Elza, and by videos, the shotgun model was to resemble like it did in the first game, but was later changed to the shorter version that was featured in the final release. The SPAS-12 that was fitted with a wooden stock and shot in semi-automatic was set to be another shotgun that was intended to be used by both characters, but was scrapped and (possibly) replaced with the Remington 1100-P. Hand Grenades were also set to be in the game, a weapon that was most likely available to Leon as Elza had the Grenade Launcher. The M202 FLASH was also set to make a return from the first game, but was later replaced by the Stinger rocket launcher. The Flamethrower was also a returning weapon and was available to Leon that was to be found in a locker in the factory. The weapon did in fact make it in the final release, but was relocated to the Laboratory. A metal pipe was set to be second melee weapon in the game, which had longer range of attack and possibly did more damage to enemies than the Combat knife, but was scrapped from the game completely. A Ruger Super Redhawk was set to be the game's magnum, and was weapon available to Leon and (possibly) Elza, but was scrapped and replaced with the Desert Eagle. The MAC-11 was to appear in the game, but it's design in the final release was slightly different, as the silencer didn't possess holes as in the retail version of the game. The HK51 was set to appear, and was supposed to be a second sub-machine gun used by both Leon and Elza, but was scrapped.
The icon of the SPAS-12 was recycled and used for the game Dino Crisis, as the version with stock of the shotgun.