How do you play as harry in Spider-Man 3 PC?

In Spider-Man 3 for PC, you don't directly play as Harry Osborn; instead, he is a supporting character. However, during specific missions, you can control him when he dons the Goblin suit. To play as Harry, complete the story missions that involve him, and you can switch to him for those segments, utilizing his unique abilities and combat style. Be sure to follow the storyline to unlock his character during gameplay.