Vin Diesel hasn’t been in a non-”Fast & Furious” film in five years, yet his fame has increased exponentially due to his major presence on social media and his iconic personality (which mainly consists of his unique voice and his ability to look really cool in action sequences). Now, with new-found fame and three “Fast & Furious” sequels as part of his career, he returns to the role of Riddick in the complicatedly titled film “Riddick.”  Thankfully, he hasn’t spaced out in the years since the last outing of this sci-fi franchise, and Diesel and crew manage to deliver an entertaining, if poorly written action flick.

Riddick (Vin Diesel) has been betrayed, left for dead and alone on a desolate alien planet. For anyone else, it’d be the very definition of doomed; for Riddick, it’s just another day in his chaotic life. When a group of bounty hunters arrive thinking their mission of capturing the criminal will be easy, Riddick sets in motion an epic adventure that takes an Agatha Christie-esque tone when some of the bounty hunters begin to meet grisly ends–and not by Riddick’s hand.

“Riddick” was made on a miniscule budget, most of which was independently financed, and the filmmakers teach a lesson to their bigger summer action movie brethren in their sparse use of over the top visuals and convoluted action sequences. The first half hour, which makes Riddick a WALL-E like figure on the planet (in that he roams alone except for a faithful pet and his wits) is surprisingly fascinating, and depicts the character’s ingenuity, cunning, and in the case of a canine creature he adopts, a part of his personality that shows he can be a gentle giant when wanted. However, once he begins to unleash carnage on those bounty hunters, “gentle” is the last word you’ll think of using to describe the fellow.

Unfortunately, the movie descends into standard non-stop action once more people get onto the planet, and not only do they bring antagonism to the plot, but they also bring terrible dialogue with them. In fact, the film’s dialogue is a high point of the film in all the wrong ways; even before the mercenary menagerie arrive, Riddick is intoning how “There are bad days, and then there are legendary bad days,” a line delivered in a way that makes its ridiculousness almost delightful to behold.

There’s still plenty of great stuff in the second and third act (Riddick’s twisted way of dispatching an antagonist involving a glass box being one of them), but it feels like a disappointment compared to the more contemplative and interesting first act. It is uneven, poorly written and even has some instances of horrific acting, but I’d be lying through my teeth if I said I didn’t have a good time during many portions of “Riddick,” and it certainly makes for a different enough experience at the movies, for better or for worse.