Once in a secure position, story editor John Semper made his first demand of the combined FOX-Marvel forces by making them buy him a complete collection of Spider-Man comics. Fox Network and Marvel Entertainment Group/Marvel Films had the idea that armed with six trade paperbacks, Semper was going to create a 65-episode series. However, he told them no, invest the money in the books and they could use them for reference. Semper got his comics and as '93 moved into '94 the story editor began researching more than 30 years of Spider-lore - building the foundation of this series.
The creative team decided not to use Gwen Stacy in this series because they did not want to use a character that was dead in the comics for over 20 years and long time fans would expect her to eventually die. Because of this decision, many of the stories were changed to the events happening to Felicia Hardy or Mary Jane Watson. However, Gwen would appear in the series finale.
When developing the series, John Semper came up with a few changes to the alien symbiote costume. This series featured a new origin for it where it came from a moon rock and bonded to Spider-Man following a space shuttle crash landing on earth. This version of the alien symbiote costume not only wants to permanently bond with its host like the comics, but also increases strength and heightens aggression. These changes were made to better tell a Spider-Man centric story with the alien symbiote costume that features additional drama for a new medium and they didn't want to adapt the multi-character crossover "Secret Wars" storyline where it bonded on Spider-Man in the comics. However, after doing some crossover and team-up episodes, they later changed their minds and Secret Wars was adapted as a three-part storyline in Season Five. It did not include any plot about the symbiote suit since that had already happened earlier in the series.
Radioactivity and all uses of the word were removed and replaced on this show with a science called neogenics, including the spider that bites Peter to give him his powers. Ironically, though, Joe Perry's theme music uses the lyric "radioactive spider blood." Double ironic considering show had to say "plasma" instead of "blood"