In 2009, they made a movie out of Garfield's Pet Force, loosely based on the book series. There was also going to be a videogame spinoff for the DS, but that got cancelled.
In the books, our heroes go to a parallel universe and become superheroes. In the movie, it's pretty much the opposite. Everyone from the parallel universe comes here to our universe, for superhero antics. "Our universe" being Cartoon World, from the CGI Garfield TV show. I've never seen the TV show, myself, so I didn't know who any of the characters were.
In the first half of the movie, the superhero Garfield rushes to find the others and turn them into superheroes. Meanwhile, normal Garfield is kidnapped by the villainous Vetvix. He's supposed to hide a power crystal from her, but he screws up. Vetvix gets the power crystal and creates a zombie army, almost at the same time that everyone gets superpowers.
Now our heroes have superpowers and a zombie army to defeat. They fight their way to the top of a tall tower, for some reason. Normal Garfield feels bad about being a loser, so he teams up with a group of minor characters, and they help save the day! Kind of. They distract the zombies and lead them all into an orchestra pit. The zombies can't climb out.
The superheroes fight with Vetvix, and they are soundly defeated. She creates a giant monster who starts destroying the city, but normal Garfield is able to defeat it with his brains, his strength, and...well, really, he wins through sheer dumb luck, but the movie tries to make it seem like he did it on purpose, so we can have a nice moral about normal people accomplishing great things.
In the end, Vetvix is defeated and is turned into a happy person. The city is rebuilt, and Garfield realizes that he should probably do interesting things, instead of sleeping through his entire life. Then he starts dancing in the sky with Arlene, to show off the 3D effects. The end.
The movie was interesting, I guess. I preferred the books, which had more science fiction and plot. The six-year-old seemed to like the movie a lot, and my wife said it was really different from normal Garfield stuff. I'd probably give it a 4 out of 10, slightly below average. It's not worth seeing more than once, and the only truly interesting part was the cool-looking giant monster.