"Killzone 3" is packed with memorable set pieces and fun vehicles. It's too bad they're all so short.

‘‘Killzone 2” felt like a road trip through the Grand Canyon with your racist uncle. The scenery was gorgeous, but every time a certain someone opened his mouth, things got ugly.

After a series of plot points and levels that felt borrowed from other popular games, “Killzone 2” [review] ended with its most annoying character, Rico Velasquez, executing Scolar Visari, the Hitler-like dictator your squad had been supposed to bring to justice. If, by the time the end credits rolled, you never wanted to see Rico again, you weren’t alone.

It feels strange, then, to say that, despite the return of Rico, “Killzone 3’s” biggest problem is that its campaign is too short.

After a little flash-forward sequence that serves as a tutorial, “Killzone 3” (rated M, $60 for PlayStation 3) picks up right where the 2009 game left off, with main character Thomas “Sev” Sevchenko, Rico and Cpt. Jason Narville dealing with the aftermath of Rico’s blunder on Helghan, the home planet of the series’ Nazi-like bad guys. Very quickly, we discover that, though their leader is dead, the Helghast’s ability to wage war is as strong as ever, and Sev, Rico and Narville quickly end up as fugitives on Helghan’s harsh surface.

Though the game’s action is intercut with scenes that depict a power struggle among the Helghast’s equivalent of a Politburo, the narrative’s focus hinges upon fleeing the Helghast, trying to contact Earth and stopping a sinister plot that Sev and Co. uncover midway through. While the game’s script won’t win any awards, Rico’s douchebaggery is kept at a minimum and the game successfully and convincingly strings together a number of unforgettable action sequences.

As I fought for my life on Helghan, I took on its soldiers in the jungles, on snowy wastelands and in trenches. I flew a spaceship, battled a giant AT-AT-inspired walker, drove something called an “ice saw” and island-hopped with the aid of a jet pack. I vanquished baddies with the usual assault weapons and sniper rifles, but also the “Killzone” series’ totally awesome bolt gun and a new weapon that levitates guys into the air before vaporizing them in a green mist.

Despite being packed with interesting equipment and widely varied missions, “Killzone 3’s” campaign clocks in at a measly six hours, seemingly the de rigueur length for first-person shooters with multiplayer components. It’s a bizarre design decision. Presumably, it took a lot of programming and quality control to ensure the eleventy different vehicles handled the way they were supposed to and that the levels accommodated them properly. So why are we just given a taste or two of each before it’s promptly discarded and never used again? It ends up playing out like the video game version of the video for Coolio’s “1,2,3,4.”

Regardless, the campaign, which supports two-player co-op locally but not online, is a heck of a ride. With the exception of one late-game firefight that felt more like trial-and-error than a test of my skills, I didn’t spend half the game waiting for it to end, making it a huge improvement over its predecessor.

Online, “Killzone 3” is competent but feels like it could use some work. There’s the usual mix of team deathmatch and objective-based gameplay, along with a nifty class and leveling system, but it needs tweaking. Maybe the smartest game type is “Operations” mode, which strings together a couple of objective-based scenarios and puts the players into in-game movies that illustrate the tide of the battle.

After having a lot of fun playing as a medic when I previewed upcoming first-person shooter “Brink,” I gave the class a go in “Killzone 3,” only to discover that my teammates stunk at playing with a medic. Time and again, one of my squadmates would go down. I’d see him on the battle and pick my way through the firefight to revive him, only to have him commit suicide so that he could respawn instantly right before I could reach him.

Then, I’d be stranded in the middle of a firefight and killed shortly thereafter. Not surprisingly, most of the players I encountered steered clear of the medic class and played as tacticians, marksmen and engineers.

“Brink” made it easy to play as and with medics by alerting downed players about how close help was at all times. By making available information on party makeup and location, and de-emphasizing kill/death ratio stats in objective-based games, “Killzone 3” developers Guerrilla Games could help ensure their audience plays the game’s multiplayer the way it’s meant to be played.

Some of this class balancing will undoubtedly be fixed in upcoming software patches, and it’s worth noting that “Killzone 3’s” support for online gaming clans will make it easy for regulars to find a group more committed to working as a team than I did. But there’s something to be said for getting it right (or closer to right) the first time.

“Killzone 3’s” campaign rates as a must-play for shooter fans, but its six-hour length may mean that players not drawn to online play or the replay value of harder difficulty levels are better off fishing for a sale.