The most disappointing thing about Riddick might not be the squandering of a flawed but consistently interesting franchise property. It might not even be the largely wooden performances, the needle-thin script, or the inexplicable bursts of blatant sexism that Riddick mistakes for levity. More than any other issue, the biggest issue with Riddick might just be how utterly boring it is, when somebody (anybody) could’ve at least had a little fun with what looks like a Roger Corman movie at times. But sans the low-rent charm.

Set some time after Pitch Black, an entertainingly bloody sci-fi flick from which we’re now amply removed, Riddick (Vin Diesel) has been left for dead on an indeterminate planet, one that clearly isn’t his home. Desperate to return to Furya, because it’s a Vin Diesel movie and therefore this is the way planets are named, Riddick becomes a man of the wilderness, befriending a dog-hyena-leopard hybrid and living in a den of many-headed, grotesque scorpions. Even though the film spends over 30 minutes on over-expository narration delivered in a gruff monotone by Diesel and various battle sequences, these are the only scenes in which Riddick comes alive. At one point Riddick spends what seems like days injecting himself with increasing doses of poison so that he can engage the scorpions in combat, and the film momentarily finds the right tone, somewhere between kitsch and the excessive tough-guy vehicles for which Diesel was once known.

Then the space mercenaries show up, and the film becomes The Thing without personality. Or Alien Vs. Predator with somehow less personality. Or something. Once Riddick happens upon a landing station for planet-hopping bounty hunters, he surrenders himself to the endlessly bickering and interchangeable crew. Composed of two rival teams of mercenaries, the crew is defined not so much by a single characteristic as by how long they’ll be in the film; those that last more than 15 are allowed meager exposition. For instance, Boss Johns (Matt Nable) is the father of Cole Hauser’s character from Pitch Black, former WWE main-eventer Dave Bautista has jokes for days, Santana (Jordi Molla) is an ugly piece of work who’s introduced as the violent owner of concubines and becomes comic relief while still attempting sexual assault throughout the film, and Dahl (Katee Sackhoff) is the token butch woman whose surname makes for a rather offensive bit of wordplay.

Don’t worry about learning who these people are, though. By about an hour into the overlong Riddick, you’ll have nothing better to do in the theater than to contemplate who’s going to die, and in what order. The “how,” usually the most interesting part of B-movie action/sci-fi/horror/whatever this movie is going for, is gory but mostly underwhelming, and the film’s endless march toward getting the two crews’ ships to fly again turns into a gauntlet of rote death sequences. Even Diesel, who’s long been a shrewdly talented actor put into bad material because he looks like a giant, muscular thumb, can’t find the notes of humor that Fast & Furious 6 distinguished itself upon. Riddick isn’t the worst film of 2013 by a long shot, but it falls into a category that might be even worse and ends up the fate of so many films in a given year: it’s completely forgettable.