Call of Duty 4: Modern Warfare left big shoes to fill, so it's not surprising that the follow-up, Call of Duty: World at War, stumbles here and there. World at War's multiplayer is a worthy successor to Modern Warfare's, but the game's campaign mode significantly lacks something when compared to its predecessor. The decision to buy World at War should depend on which of these aspects you value more.

You play the role of two different privates fighting on opposite sides of the globe during World War II. Mills is a US Marine operating in Japanese territory while Petrenko is a solider in Soviet Red Army, fighting their way to Berlin. The Soviets definitely have the more interesting objective of storming the Reichstag and bringing Germany to its knees, while the Americans are more or less just taking out whatever Japanese soldiers they come across, with no awe-inspiring objective behind the whole operation.

You're a World War II soldier - again.

Each side of the campaign is narrated by the squad's respective leaders who serve as the primary characters in the game's plot. Reznov of the Soviet army, voiced by Gary Oldman, is an eccentric sergeant and seems to have a crush on you after you assist him in the very first mission. Kiefer Sutherland voices Roebuck, who is the sergeant in command of the US Marine squad. He's rather moody and fills the entire Japanese half of the campaign with angst. The depressing narrative is fitting given the dark and violent context of the Pacific theater in World War II, but it never makes for an interesting story. The climax of the game is fairly effective, but it all pales in comparison to the immersive and exciting plot of Modern Warfare.

Call of Duty 4's gameplay has gone relatively unchanged in World at War: both the controls and campaign are structured nearly the same. Again, the silent soldiers you play as are treated as one-man armies with your squad demanding that you carry out every single objective on your own. The enemies are aware of your important role and will often ignore your nearby allies to attack you. The abnormal amount of importance placed on your character's role makes the game more fun, but it often leads to many scripted events that will repeat over and over again upon your death.

Even on the regular setting, the game's difficulty is inconsistent, shifting between overly simple to frustratingly difficult. Since levels mostly take place in war-torn cities or dense jungles, they appear to be large and open. However, the missions are very linear with conveniently placed obstacles blocking off any potential deviations from the main path. Save for one of the two vehicle missions, the game's levels are never much fun. They all make attempts at the same type of exciting immersion that Modern Warfare successfully implemented, but all of these attempts feel forced and fall flat. Between the erratic difficulty and the boring nature of the missions, World at War's campaign is a terrible single-player experience. However, the multiplayer is just as great as, if not better than, Modern Warfare's.

If you've played Call of Duty 4 before, you'll be very familiar with the multiplayer offering in World at War. You create classes by equipping primary and secondary weapons along with four perks which grant the class special abilities. Many of the perks return from Modern Warfare, but some have been altered. For example; Last Stand allowed players to wield their pistol after they've been gunned down, now Second Chance does the same and allows other players with the same perk to revive them. New options have been introduced as well, like Toss Back, which resets a triggered grenade's timer when you pick it up.

As you kill enemies, accomplish objectives, and complete challenges during matches, you'll obtain experience points which will increase your rank. Each rank brings with it new challenges, perks, or weapons. You can also unlock attachments for each weapon by getting enough kills with specific guns. The guns themselves are the biggest difference between World at War and its modern counterpart. Since the game takes place more than sixty years earlier than its predecessor, World at War features the weapons of the era.

Most have very poor default sights and smaller clips than you might be used to, but they can be improved with the various attachments. There are also bipods which allow you to mount heavy machine guns, and bayonettes which extend the reach of your melee attack. The bolt-action rifles, which serve as the game's sniper rifles, do not come with a sniper scope. Instead, you must unlock the scopes by using the weapon in combat first - a fairly slow and aggravating process. The Prestige feature also returns, this time unlocking extra custom class slots every time you choose to reset your stats.

Much like in Call of Duty 4, getting several kills in a row still grants you assistance bonuses, but there are a few changes in this time around. Three kills allows you to call in a recon plane, revealing the location of enemies on the map. A five-kill streak calls in an artillery strike which lasts longer than Modern Warfare's air strike. At seven kills, players can call in a pack of attack dogs which seek out enemies. The dogs themselves are quite susceptible to bullets, but are fast and can take out an enemy with a mere two bites.

Tanks and vehicle perks are a new addition to the multiplayer component. Several levels contain two or more tanks which can hold up to two players. The driver mans the cannon, while the passenger controls the gun turret up top. There is a fourth perk slot for specific vehicle abilities such as Ordnance Training which reloads cannon shells faster. The tanks are tough, but can be taken out by explosives or using concentrated gunfire. You only receive the regular amount of experience points for destroying a tank with someone in it, so it's obvious that the game is encouraging players to use them, as they can be very powerful in the right hands.

In addition to the other changes, there is also a new mode that is unlocked after completing the campaign which pits you against Nazi zombies in a barricaded building. Your goal is to survive as many rounds as possible. The zombies never stop coming, but you can invite some friends along to help you survive. You earn points for hitting and killing zombies and can then use those points to purchase new weapons or unlock more sections of the building. You can also earn points by reinforcing your barricades, but eventually the zombies will come quicker and in greater numbers, rendering this useless. They also grow in strength as the rounds progress, which makes this mode more difficult the longer you survive. It's not the deepest addition, but it can serve as a fun distraction between multiplayer matches.

The maps are significantly larger than in Call of Duty 4.

Aside from the fact that the maps in World at War are much larger and diverse than in Modern Warfare, the multiplayer mode is virtually the same with a fresh coat of paint. You'll fight in country villages, mountain temples, Japanese castles, grassy fields, and more. None of the stages are symmetrical, and only two are somewhat similar to arena maps. There are a few environmental objects that appear interactive but aren't, such as ledges that can't be climbed. It's also odd that certain explosives can't seem to breach the weakest of obstacles such as doors and windows. When compared to other first-person shooters like Battlefield: Bad company, which features dynamic environments full of destructible objects, World at War's levels feel a bit too static.

Despite the fact that bushes and tall grass look pixilated when you are hiding in them, World at War's graphics are solid. The game sounds just as excellent as well, and it's obvious that the developers went to great lengths to get accurate recordings of all the weapons. Aside from a few musical pieces that incorporate rock instruments, the music is also effective. It just sounds strange to hear an electric guitar riff while veterans of World War II are being thanked on-screen. Soldiers have a wide variety of things to shout across the battlefield. They'll even shout level specific statements in multiplayer such as "they're in the round hut!" All in all, the game makes good use of the Call of Duty 4 engine.

There was a small bit of controversy surrounding the Japanese half of World at War's campaign, but you could easily avoid the experience altogether and be totally satisfied with the multiplayer. World at War offers more of the same gameplay found in Call of Duty 4 but with some World War II flair and small improvements here and there. While it's a shame that the campaign isn't as good as its predecessor's, World at War sticks to what made Modern Warfare great: a solid multiplayer experience that can last you months.