Actor John C. Reilly has landed a writing credit in his new movie Wreck-It Ralph after working closely with animators to develop his character.

The Oscar nominee was initially wary of signing on to voice the titular video game villain-turned-hero in the upcoming film, but Reilly admits he put his whole heart into the movie and it turned out to be one of his favourite projects.

He tells the Associated Press, "I'd heard that making animated movies for actors was often kind of this isolated, strange experience. You go in and do your lines, and then you react to recorded lines from other people... I was like, 'That doesn't sound fun at all.'.... (But) it turned into this dream job... something I can be really proud of."

And because the Chicago star spent so many hours demonstrating monstrous Ralph's movements and gestures for the motion studies team, as well as improvising some of his lines, the actor was granted a special mention in the film's credits.

He adds, "I was like, 'This is how he gets up from a chair. It's like an eight-step process. It's kind of like an elephant raising itself off the ground.' Every single gesture and expression that a character makes in an animated movie means hundreds of hours, if not thousands of hours of work from a bunch of people so I was really happy that they made the commitment to do those little subtle things to really finish out the character in a really detailed way."