Comic stories tend to involve sending key characters into alternate realities, where they meet their often evil or psychotic alternate selves. Not the case with Spider-Man.
Spider-Man: Shattered Dimensions revolves around a magic tablet that's been split across four alternate realities, and the villains from each reality has a fragment. Madame Spider doesn't like this, so she summons the four Spider-Men of each reality to fix the mess. Every universe comes with at least one alt costume, which are borrowed directly from the comics; Manga Spider-Man (cringe) will be making his video game debut in the Ultimate.
Check out the launch trailer for a glimpse of each Spidey, and play "Guess Who" with the villains. Juggernaut and Deadpool don't count.