Director Joss Whedon teases that the ending of Avengers: Age of Ultron is going to be pretty over-the-top.

Whedon tells Yahoo that, despite his best efforts, the film just kept getting bigger.

“[Avengers: Age of Ultron] got larger than the first film,” Whedon says. “I didn’t mean for it to get larger, but the climax that I pitched was completely unhinged and nobody said no, so that’s that.”

With the Marvel Studios films jumping genres – Captain America: The Winter Soldier being a spy thriller, and Ant-Man looking like a heist film – Whedon describes Avengers: Age of Ultron as a sweeping adventure that encompasses several other genres.

“To me, adventure film is the best way to put it,” he says. “Then science fiction, action, western, war, woman’s picture, horror movie … I’m not kidding; every single one of those things is in there.”

Avengers: Age of Ultron opens May 1.