Despite sales remaining strong, it's safe to say that Call of Duty has been in a bit of a slump as of late. Although Advanced Warfare was well received, there were some rough patches, and most CoD fans still shudder whenever they hear the word Ghosts. Now it's time for Treyarch to pick up the mantle, and boy has the studio done well with it.

The most obvious addition to Call of Duty: Black Ops III is the new movement system, overhauled from Advanced Warfare's slightly more primitive exosuits. You can still use your jump pack to sky jump, but now more abilities have been added: you can boost-slide along the floor as well as run along walls. The new, extremely fun Free Run mode – made up of four courses to try and beat – will help you get to grips with the system, but it shouldn't take long. After all, it's very intuitive and makes you feel very much in control, and the fact that you can shoot while doing all of this makes for some great moments in the game.

Swimming has also been added to the mix; water is no longer a toxic jelly that kills you on contact, but it isn't implemented that much. In the campaign, there are barely any swimming sections, and only a couple of multiplayer maps have water. Still, the latter statement is for good reason, as it's easy to exploit this mechanic on modes such as Capture the Flag – on the Metro map, you can simply grab the flag and swim underwater where it's hard for people to spot you.

Let's start with the mode that most people buy Call of Duty for: the multiplayer. There's a huge amount of stuff to do here with 12 maps, 17 modes/playlists, as well as countless customisation options and new systems. Most of the maps are quite well suited to the new movement system. In many, there are plenty of wall-running shortcuts, verticality, and flanking routes – but some maps seem like they've been ripped straight out of another Call of Duty game. This is a little disappointing, because what makes Black Ops III's multiplayer so fun is how fast-paced and vertical it is, but when you're relegated to running around without any opportunities to parkour, it really strips the fun-factor away and turns it into the boring cycle of spawn, kill, die, respawn that has worn thin in recent years.

However, the sheer amount of playlists available in multiplayer ensures that everybody has something to play. All of the modes from previous games return, from Team Deathmatch to Domination, Search and Destroy to last year's Uplink, as well as four Hardcore modes, Ground War, Mercanary Moshpit, and a limited-time Nuk3town-only playlist that will likely resurface in the future.

There's also a new mode, Safeguard, in which one team must defend a robot as it walks to a destination, while the others try to prevent it from reaching its objective in five minutes. The robot can't be destroyed, but it can be disabled for a short amount of time and doesn't move if there isn't a team member nearby. The catch is that, if the first team manages to get the robot to the objective, the other team has to beat that time or lose the round.

It's a cool idea that works a lot better on some maps rather than others, as the pre-determined route that the robot takes often goes through bottlenecks that are easily exploitable and can tip the odds in favour of the attackers, most noticeably on Evac. But that's really the main theme with Black Ops III multiplayer – it's often very fun and always exciting, but some mode and map combinations can turn things sour.

Also added is the new Arena mode, which is essentially a Ranked mode. You can either play with eSports rules, in which players can choose to ban or protect certain weapons and there's a Specialist (more on that later) draft before every match, or you can just play using the standard Call of Duty format.

Black Ops III's multiplayer customisation is also excellent. The Pick 10 system, in which you're allowed to pick ten items for your class, returns and ensures that everything is balanced – you can sacrifice your perks or grenades in order to get more attachments, for example. However, it goes far beyond that. The new Gunsmith option allows you to customise the way that attachments look and how they're arranged, while Paintjob allows you to personalise your gun with decals, colours, and other such things along with the usual unlockable camos. It's great to have so many options to express yourself, and the fact that you can upload and download your chosen camos adds a whole new dimension to the multiplayer.

The new Specialist system also adds some spice to proceedings, as it allows you to choose a Specialist that affects both the look of your character and your special ability. As you level up, more Specialists unlock, and it's good to see that there isn't really an overpowered character that everyone uses – at least not yet. Don't get us wrong, Gravity Spikes – which plunge into the ground causing a killer shockwave – is very powerful, but all of the other abilities have their own uses that are equally as good. Vision Pulse allows you to see who's near you, while the Sparrow is an exploding bow and arrow that has a long reload time but deals big damage. You can also unlock more cosmetic upgrades for your Specialist, as customisation is a huge factor in Black Ops this year.

Guns, attachments, perks, and wildcards are all still unlocked by levelling up, but you'll now need to spend Unlock Tokens in order to get them. It's slightly annoying, considering that you have to grind a little more after you've unlocked a gun, but it's certainly no biggie. You can also unlock more cosmetic upgrades by buying Supply Drops, which can be bought with Cryptokeys that unlock regularly. They aren't given out generously, though, so hopefully microtransactions won't be implemented at some point. Still, they don't affect much – you won't miss out on anything special if you don't have enough Cryptokeys.

Campaign mode has always been a little neglected in the Call of Duty franchise as of late, but once again Treyarch breaks that rule – this is quite simply one of the most complex and comprehensive campaigns in franchise history. First of all, it's four player co-op – offline or online – which is always an excellent way to play, and feels more open and less like a boring corridor shooter. Level design, while having some vehicular on-rails sections and set pieces, has been made to better accommodate the new movement system, adding verticality, different pathways, and tons of flanking routes that make it great to play as a team. Realistic mode – in which one bullet kills you – adds some tension to the missions, and gives you a sense of real achievement after beating it.

A new feature to the campaign is Cyber Cores, which are abilities that you can use to gain an advantage in the battlefield. For instance, you can use swarms of Fireflies to distract enemies and open them up to attacks, or jam your opponent's weapons. Meanwhile, Tac-Rigs are alterations that you can make to your suit – the ability to wall-run and boost jump can be found here among other things.

There are a couple of pacing issues in the missions themselves, and the story is once again forgettable. You play as a US supersoldier fighting against a terrorist organisation known as the CDP, with you and your buddies jetting off to places such as Zurich and Singapore in order to stop them.

The main problem is that, for a campaign that's supposed to be open, there are way too many cutscenes and pointless dialogue sequences that just get in the way of the fun. Also, many of the action sequences are in cutscenes, which also takes away from entertainment factor of it – watching an explosion isn't as cool as setting it off. Still, there are some pretty great sequences: zip-wiring across the Solar Trees in Singapore, as well as the battle on the train in Zurich, are certainly exhilarating to play.

In between missions, you return to the Safehouse, in which you can customise the look of your character and spend the abundance of Unlock Tokens on weapons that you've unlocked by levelling up. Overall, it's cool that so much effort has been put into the campaign, subsequently making it a lot more worthwhile to play. After completing the story, you can even play it back in Nightmare mode, which changes the objectives, story, and dialogue to a zombie apocalypse theme, with the enemies themselves becoming zombies.

Speaking of Zombies, a lot has been added to Black Ops' most famously outlandish mode, too. The map this time around is Shadows of Evil, which seems to have taken a Cthulhu theme. It has some great voice talent, with Jeff Goldblum and Ron Perlman lending their dulcet tones to the characters, and the mode itself is a lot more complex now.

Most notably, Gobblegum has been added. These can be unlocked by levelling up – yes, Zombies has its own levelling system too – and are gotten in Shadows of Evil's various Gobblegum machines. You can choose five different Gobblegums that are available to you before the match, one of which is randomly selected and given to you whenever you pay up the 500 points necessary, and some are real game-changers. For instance, one allows you to keep your weapons after you die, while another increases your bleeding-out time.

These Gobblegums can be obtained in Dr Monty's Factory by spending Liquid Divinium, which is obtained in matches. The more Divinium that you spend, the rarer your Gobblegum will be. Normal Gobblegum can be used infinitely, but the rarer Mega Gobblegum has limited uses, but is much more powerful.

As you can perhaps tell, Shadows of Evil is a heck of a lot more complex than other Zombies maps; the sheer abundance of Easter eggs and other malarkey can make it overwhelming the first couple of times that you play. You'll probably question why "becoming the Beast" is an option, why you should perform Rituals, and what a Fumigator is – but they all become clear as you play on. We won't spoil their purposes for you, though, because finding out all of these little quirks is what makes Zombies so fun.

Other than that, Zombies still has the same principle: shoot the undead, survive for as long as possible, and spend your points on guns, power-ups, and special drinks. Since the new movement system isn't present in Zombies, it does feel a little sluggish and clunky in comparison to the other available modes, but once you get into it, it becomes a delightful romp.

Conclusion

The sheer length of this review should tell you that Call of Duty: Black Ops III is filled to the brim with content. While there are some low points and pacing issues, the campaign's customisation, freedom, and verticality make it excellent to play with friends. Meanwhile, mutliplayer has more customisation and replayability than ever before, and Zombies is brilliant in its complexity and difficulty. While Ghosts may have bitten the bullet, Black Ops III reloads the franchise into a new, brighter era.