Mars Attacks! could have been awful but settles for mediocre.

The film jumps between several storylines as aliens from Mars attack Earth. We follow the President and his staff, a pair of television personalities, a family in rural Kansas, a sleazy Las Vegas developer, and a washed up heavyweight boxer. Jack Nicholson leads an all-star cast as both the President and the Vegas developer.

The studio advertised the film as spoofing 1950s science-fiction pictures, but it doesn’t play that way. Among the cast, it’s telling that former NFL fullback Jim Brown seems the most comfortable. He plays the boxer reduced to dressing as a pharaoh for an Egyptian-themed casino. When the Martians attack, Brown heads out to reunite with his ex-wife (Pam Grier) and kids. He gets some help from Tom Jones, who plays himself. There’s a wonderful scene where Brown asks Jones, “Do you know how to fly a plane?” to which Jones replies, “Of course! You got one?”

This sort of goofball casting matches the goofy sci-fi premise. Brown and Jones both seem aware of their shortcomings as actors, and their stiff performances are genuine and entertaining.

It’s a glimpse of the movie I suspect director Tim Burton wanted to make. He seems less interested in spoofing the genre than recreating it.

That’s not a bad idea, but no one told the big-name cast. Few appear to enjoy the material. Most convey a sense of condescension, their performances screaming “I’m overacting on purpose!”.

Did they have a choice? Unlike Brown and Jones, the rest of the cast can’t pretend they’re amateurs. And playing it straight wouldn’t have helped. Pam Grier plays her role with such conviction, her scenes feel spliced in from a different film. Martin Short plays his role as though he were in an overt comedy, to similar effect.

At least they got the Martians right. The 1950s films featured serious monsters cobbled together with silly effects. Here, we get cartoonish villains brought to life with no visible wires, seams, or zippers. In my favorite scene, the Martians laser a national monument, catch the falling debris with their flying saucer, and redirect the rubble onto a fleeing tour group.

Still, Mars Attacks! underwhelms. It’s a rare movie that would be much better were it much worse.