Putting out a follow-up every year is the sort of crunch-time madness that's usually reserved for sports offerings. But for the third year running, Insomniac Games has put together an entry in its excellent Ratchet & Clank series. This installment, subtitled Up Your Arsenal, doesn't reinvent the usual single-player mechanics. Instead, this year's iteration makes incremental changes to things like weapons, locales, and so on, while wrapping the game in a new story. It also adds a great, objective-based multiplayer mode that can be played by up to eight players online. All things considered, Ratchet & Clank: Up Your Arsenal is great fun, combining some solid platforming action with a lot of exciting combat.

Ratchet & Clank's single-player will be instantly familiar to fans of the series. The multiplayer, however, is all-new.

For those of you who haven't been following the series, Ratchet & Clank is a very combat-focused platformer that gives you a lot of wild weapons to play with. You play as Ratchet, some sort of big-eared alien thing, and Clank, his robot companion. For the most part, Clank sticks to Ratchet's back. However, from time to time, the duo will separate. When this happens, you'll take control of Clank by himself. The action is fairly standard for a platformer in that you'll be doing a lot of jumping around and hitting things with your standard wrench attack. The weapons in the game do change this up a lot, though.

The focus on combat means that you'll spend a lot of time blasting enemies with a wide variety of instruments of destruction. Some from the previous games return here, and you can even use some of them for free if you have save files from the other games on your memory card. Most of the weapons fall into pretty standard categories. You have a grenade launcher, a standard rapid-fire-shot, and a shotgun. You'll also be able to create tiny black holes, emit deadly bolts of electricity, turn enemies into sheep, snipe enemies from a distance, and so on. Some weapons fall into support roles, like those that have the ability to create turrets, summon batches of robots to attack foes, or even create small shields to hide behind. Weapons also gain experience and features as you use them. The five different levels of any one may just make it more powerful, but some gain the ability to induce shock damage, offer lock-on capabilities, and more. This variety gives you a lot of different ways to take on the opposition, but you'll find that the standard weapons, like the shotgun and machine gun equivalents, are definitely the most useful.

The single-player thrusts you right into the action, assuming that you already know everything about Ratchet and Clank's exploits up to this point. Clank, it seems, has gone on to become a television star. But the world falls into peril once again, this time from an evil robot named Dr. Nefarious, so the duo springs into action to stop the mad doctor before his plan to turn all organic life-forms into robots comes to fruition. Along the way, you'll join up with the ever-popular Captain Qwark, his creepy-looking one-eyed monkey, and a cast of characters--new and old--that assembles the Q-Force, Qwark's new squad devoted to fighting Nefarious.

Ratchet & Clank have all of the same moves they had last year, along with a few new ones.

Nefarious has quite an army of enemies for you to gun through. Much of Up Your Arsenal's combat requires you to be fairly patient and rely on cover when possible. Your enemies will do the same, so you'll frequently have to either wait for them to pop out from behind a wall or just run up on them, guns blazing, and hope for the best. While you can get away with full-frontal assaults for most of the game, the later levels really punish sloppy play, forcing you to take things at a more methodical pace or watch as you're repeatedly crushed by robots, ninja robots, gladiator robots, robots with maces for arms, hovering robots with spinning blades, giant robots, tiny robots, or the occasional slimy-looking alien beast. The enemies may look different from level to level, but aside from increased resilience to your shots, the tactics remain mostly the same.

The general structure of Ratchet & Clank hasn't really changed too much over the years. Up Your Arsenal keeps most of the elements found in the last game, with some slight changes here and there. Your overall goal is to stop Nefarious, of course, and you'll accomplish this by taking on a host of missions all over the galaxy. Most of these missions simply require you to get to a specific point in a level, at which time you'll see a cutscene that advances the story and gives you someplace else to go. Early on, you'll encounter a spacecraft called the Phoenix, which acts as your home base. However, your trips back to it usually just involve seeing another cutscene that gives you the location of your next objective. The cutscenes are put together very well, and they showcase the game's great-looking character models. A handful of them are pretty funny, too. One sequence is the latest music video from a female robot called Courtney Gears, and everything, from the synchronized dance moves to the song's epic pop production and incredible devotion to extreme overuse of an autotuner, is a spot-on parody of recent pop music.