After about seven years between their development, the maps of Rocksteady’s Marvel’s Spider-Man are vastly different in size. These two games have many similar elements in of gameplay and story; both feature popular superheroes whose main movement mechanics are well suited to open-world traversal, have combat and stealth mechanics mixed into a long linear narrative with optional side missions, and each story requires the character to move quickly between distant areas of the map, using the open world to tell the story and challenge players. However, despite their similarities, there is a big difference in scale between Batman: Arkham City and Marvel’s Spider-Man.
In 2011, Rocksteady Studios released Batman: Arkham City. This game, along with its predecessor Arkham Asylum, set a bar for licensed superhero games that remains in place to this day. Both the story and gameplay of the Batman: Arkham series have been praised by casual fans and critics alike. Arkham City is considered one of the best games of its type, so it's no surprise many other open-world titles with similar gameplay have imitated or copied elements from Batman: Arkham City, even if they aren't superhero games. Marvel’s Spider-Man is no exception. Released in 2018, Marvel’s Spider-Man was inspired by Batman: Arkham games. Marvel’s Spider-Man has been praised for these elements and enjoyed widespread success.
Because of the seven-year difference between the games’ development and release, Marvel’s Spider-Man is a much bigger game than Batman: Arkham City. Marvel’s Spider-Man only lets the players visit Manhattan Island in New York City. Its overworld is about one-fourth the scale of Manhattan, making it (via Twinfinite.net) about 11.9 square kilometers (or 4.6 square miles) of space. Meanwhile, the overworld map of Batman: Arkham City is about one square kilometer (0.38 square miles), assuming that one takes Rocksteady's word for it that Arkham Knight (clocking in about 5 square kilometers or 1.93 square mile, as per Redditor shtevay's exhaustive analysis) was five times as large as Arkham City. That makes the map in Marvel’s Spider-Man roughly twelve times the size of Batman: Arkham City.
New York in Marvel's Spider-Man Is Much Bigger than Batman: Arkham City
Even for the time between their release dates, the difference in scale between these games is enormous. Batman: Arkham City and Marvel’s Spider-Man have similar mechanics and story requirements, so it would make sense if the games had similar map sizes. However, Marvel’s Spider-Man has been following a trend that other games in the Batman: Arkham series have followed as well. Open-world maps in games have generally become bigger as technology improves. In fact, Marvel's Spider-Man 2's open-world map will be bigger than the first game. And the final main title in the Batman: Arkham series, Batman: Arkham Knight, is roughly five times the size of Arkham City and came out three years before Marvel’s Spider-Man. Perhaps if Batman: Arkham City had been made at the same time as Marvel’s Spider-Man, its map would be similar in size.
It’s also worth noting that Gotham City, where Batman: Arkham City takes place, is heavily based on New York City, despite some artistic license. However, Marvel’s Spider-Man is explicitly set in that real-world location, so it makes sense that more resources would be put into making the overworld map resemble the actual place. At the time, Rocksteady didn’t have access to the same technology as Marvel’s Spider-Man, and it had to take more creative liberties when deg a playable space. These may be the reasons why Batman: Arkham City’s overworld map is less than a tenth the size of Marvel’s Spider-Man.
Source: Twinfinite.net, shtevay/Reddit