We might as well come right out and say it: Pokémon GO is a genuine phenomenon, one of those rare moments in video game history (think Pac-Man, Donkey Kong or Tetris) where the entire population of the planet seems to be hooked. That might sound like the most extreme hyperbole imaginable - especially when you consider that the smartphone app isn't even a month old at the time of writing and has endured some notable teething troubles since launch - but from where we're sitting it's almost indisputable.

Everywhere you go people are talking about it. It's on the TV. It's in your local newspaper. We've been driving through towns in the dead of night and have spotted people huddled around notable landmarks playing it. This is the kind of gaming event that doesn't happen very often - in fact, we're hard pressed to think of any kind of precedent which comes close - but as any mobile phone owner will tell you, there have been other phenomenons in the past which have enjoyed incredible exposure and success only to fade after a year or so. What makes Pokémon GO any different? Quite a lot, actually.

On a simplistic level, Pokémon GO takes the famous and insanely lucrative monster-catching franchise and transplants it into "the real world" using a combination of your mobile phone's GPS functionality, Google Maps data and your handset's camera, the latter of which is used to created an Augmented Reality environment in which 3D rendered Pokémon appear directly in front of you, waiting to be ensnared in one of those iconic red and white Pokéballs. Each of these components isn't groundbreaking when taken on its own; Nintendo dabbled with AR gaming when the 3DS launched, while Ingress - also developed by Pokémon GO studio Niantic - uses real world maps as the basis for its gameplay. However, no smartphone title has been so successful at pulling all of these elements together to create a compelling experience, and the fact that Pokémon are at the center of that experience is perhaps what has given Pokémon GO such astonishing mainstream appeal; even your grandmother probably knows what a Pokémon is, after all.

Unlike the traditional console Pokémon titles, there's little in the way of preamble or exposition here. Once you've created your user account and decided on what your avatar looks like (with limited options) you're placed on a map screen which represents your current surroundings in the real world. That means you can walk around your own neighbourhood looking for Pokémon, interacting with Pokéstop markers for special items and pinpointing the gyms which become your focal point later in the game. Initially these are off-limits as you have to raise your avatar's level to 5 in order to enter them; this is done by capturing Pokémon or visiting the aforementioned Pokéstops.

Pokémon appear on the map and must be tapped in order to trigger the capture mini-game. It's here that you're presented with an AR display, showing the Pokémon leaping around your current location. Sometimes you'll have to move your phone around to find the monster, and once pinpointed you have to flick a Pokéball onto their head to capture them. It sounds simple, but you have to judge the distance and throw with the correct force to gain a hit, and some Pokémon will fight back by repelling your projectile. To make things easier you can disable the AR view, which keeps the Pokémon dead-center at all times; it's less immersive this way, however - the whole "Pokémon in the real world" angle is lost. Some Pokémon will burst free from the Pokéball even when captured, but later in the game you gain access to berries which you can feed them to make them more docile. Stronger Pokémon also require more powerful Pokéballs - again, these are unlocked later when your avatar has attained the appropriate level of experience.

Capture a Pokémon and it is added to your Pokédex, just like in the mainline game series. You can then use Stardust - a commodity which is dished out as a reward for capturing monsters, as well as experience points - to level them up. As each Pokémon's Combat Power rises, so too does the Stardust cost of levelling them up. You're also limited by your own experience level - it's not possible to fully level up some monsters unless you're a pretty adept trainer yourself. Just like the console games you can evolve your Pokémon as well. This requires candy, which is specific to each Pokémon breed and is also given out after capture. Levelling up doesn't require Stardust and can be done at any time provided you have enough candy - you can also exchange unwanted Pokémon for a single piece of candy specific to that monster.

Tracking down Pokémon is merely one aspect of Pokémon GO, however. As you trot around the real world you'll spot blue cubes - otherwise known as Pokéstops - which are anchored to notable locations in the real world (usually churches, monuments or other places of local interest). These dish out resources such as Pokéballs, berries, healing sprays and revival items, and take a few moments to recharge before they can be used again. From time to time you'll be handed an egg at a Pokéstop - these are integral to gaining some of the title's rarest Pokémon. You place the egg into an incubation chamber to hatch them, and each one has a distance attached - 2km being the smallest, 10km the largest - and that denotes the range you have to walk before it cracks.

Pokéstops are important for another reason - they can be used to pull together a large group of players by activating the Lure Module item. This causes the Pokéstop to change appearance on the map, a visual effect which can be seen by all nearby players. The module increases the number of Pokémon nearby, making it an attractive hunting ground for budding trainers. This effect lasts only for 30 minutes, but we've been amazed at how quickly it attracts a large crowd, even when it's in quite a remote location. You can also attract monsters by using the Incense item, but the effect is limited to just you and thereby lacks that interesting "social" edge.

Reaching experience level 5 marks the next phase of Pokémon GO. You become eligible to enter gyms, and have to pledge your allegiance to one of three teams - Valor (red), Mystic (blue) and Instinct (yellow). The objective is to take over as many gyms for your team as possible, but even in a lightly-populated area this is easier said than done. Gyms can be strengthened by multiple players of the same team, but an attacker is able to take on a single defending Pokémon with six of their most powerful monsters. That means that gyms change hands constantly, with only the most powerful (and reinforced) locations able to repel invasion. Gyms have a prestige rating which is bolstered by defending it from attackers, but diminished by successful incursions.

As you fill out your Pokédex you'll be spending a lot of time around gyms or in search of them, as they provide a solid means of gaining experience and increasing the prestige of your faction. However, you're limited by the need to revive fallen Pokémon and heal the wounds of others, so you can't simply stand outside a gym and spam it with attacks - healing items can only be obtained from Pokéstops, so you're encouraged to walk around and explore in-between assaults.

Combat in a gym is different from the turn-based action we're used to in the mainline Pokémon series. Events unfold in real-time, with a tap performing a normal attack while a "tap and hold" will trigger a special move unique to that monster, provided you've charged up your power meter. You're also able to dodge left and right with a swipe in the relevant direction, but there's not a massive deal of strategy involved; it's basically a case of whose Pokémon has the higher CP rating. You can swap out your Pokémon for another if you so choose - a handy option when you realise that type plays a huge role here. You'll see messages pop up on-screen if your current Pokémon is "not very effective" against its rival, and leaving them on the battlefield in these cases is naturally a poor decision.

Taking into account that Pokémon GO is free to play, it's a given that in-app purchases are included, but Niantic has struck the right balance here - there are no items which can give you an unfair advantage over other players, and it's certainly not a "pay to win" situation. You can purchase more Pokéballs - something we've not even had to consider doing yet, given that they're handed out at pretty much every Pokéstop - and buy lucky eggs, which increase the amount of experience you earn for a short time. It's also possible to buy Lure Modules, but these are also handed out occasionally when you level up. Extra space for items and Pokémon is also an option, and you can buy an additional incubation chamber so you can hatch more than one egg at a time. Incense can also be purchased for real-world cash.

It's often said that many freemium smartphone titles are kept afloat by a very small percentage of "whales" - users who have no qualms about splashing money in-game - but the irony here is that by treating its players with respect and not exploiting their interest in the game, Niantic has created a situation where in-app purchases are much easier to stomach, and therefore more likely to be purchased by casual users. Valuable items such as incense and Lure modules are handed out whenever you level up, which means they're never locked behind a paywall. However, should you need one urgently, then you can use real money. It's a fair system; so many other developers would have restricted such items to paying customers only.

Because you're awarded coins for having Pokémon installed at gyms, you can potentially earn the game's premium currency without having to spend any real-world cash, but it would take quite a while as the amounts handed out are quite small. Even so, Pokémon GO's IAPs never feel like an invitation to "break" the game by ruining the challenge; to be honest, the people who truly have an advantage here are the ones who live in large cities with an abundance of Pokéstops, gyms and monsters to find (although you could argue that the increased competition from other players makes securing gyms more difficult). If you live out in the middle of nowhere and don't visit any large towns or cities on a regular basis, then Pokémon GO's appeal is certainly going to be diminished. It is a game which thrives on social interaction, as has been evidenced by the numerous stories about large groups of people massing together to capture the same rare monster, or collectively take over a gym for their team.

Another big plus point for the game is the fact that it gets you out of the house. While the health benefits of this are easy to see, there have been anecdotal reports of people experiencing an improvement in their overall well-being. The concept of exercise triggering good feelings is hardly a new one - Nintendo has even been here before with its Pokéwalker accessory (which would later evolve into the Wii Fit Meter) - but when you've got a game which actively encourages you to take long, beneficial walks and explore the world around you, it's clear that something very new and exciting is happening here. Of course there are some risks involved - including robbery and injury, as has been reported lately - but thankfully these are far outweighed by life-affirming stories of people forging new friendships and collectively coming together in the pursuit of Pokémon.

We couldn't possibly review Pokémon GO without addressing the elephant in the room - namely the game's occasionally crippling technical problems. While no one could honestly have predicted the game would be as popular as it has been, it's clear that Niantic has massively underestimated the amount of server power needed to keep Pokémon GO running smoothly. In the interests of balance, when a game is hitting daily user figures that are occasionally higher than Twitter, some issues are inevitable and couldn't have possibly been considered a likelihood beforehand.

Players have trouble logging on and sometimes when they do manage to connect to the game, constant loading issues mean that nothing can be interacted with, or capture attempts fail because the game freezes. At the time of writing the only way to overcome such problems is to shut down the app and reload, which often means losing progress and being pushed to the back of the queue when it comes to logging on again. That said, with each passing day we're having less problems connecting here in the UK time zone.

Were this a normal video game, we'd have to seriously mark down Pokémon GO for such problems. However, it's anything but a 'normal' game. Smartphone apps are updated constantly and the chances are if you happen to be reading this a few months into the future the server problems which currently blight Pokémon GO will be a thing of the past. Besides, even with these irksome faults, we've had more fun with Niantic's title than any other smartphone outing we can recall; it's so effortlessly addictive and compelling that it's easy to forgive its technical difficulties. The simple notion of tracking down Pokémon - something that is surely hard-coded into the DNA of many Nintendo fans - twinned with real-world travel and exploration has created a "game" which is accessible and appealing to practically everyone, as has been evidenced by the overwhelming success it has enjoyed in a relatively short space of time.

Conclusion

Given the fact that Pokémon GO has more than its fair share of problems at the moment, you might be looking at that number at the bottom of the review and wondering exactly what we're smoking. However, we've judged this title on the premise that in the not-too-distant future Niantic will get a grip on the server troubles and present a more stable experience; it's obvious that the level of demand simply wasn't anticipated.

Even with the log-in issues and patchy performance, we've still had some truly amazing experiences with this app, such as the thrill of capturing a rare Pokémon in an unexpected place and meeting up at a Pokéstop with like-minded players to create new (and admittedly fleeting) friendships. While you could argue that this initial burst of popularity will pass, there's a staggering amount of potential in the concept; with only the first generation of Pokémon currently included (and finding all of those is tricky) there are around 600 other beasts which can be added in waves, and even when that happens the constant battle for gym domination and the scope for evolving your menagerie of monsters offers weeks, months and perhaps years of solid entertainment, all of which is at your fingertips 24 hours a day due to the fact that Pokémon GO resides on your phone - the only piece of tech that pretty much everyone on the face of the planet keeps within constant reach.

Niantic's game is a revelation in many ways, and the big N's imprint can also be seen throughout the experience. Nintendo's true smartphone revolution begins here.

App version reviewed: v1.0.2