The town of Banff, Alberta, Canada, is a bustling little holiday destination, perfect for hikers in the summer months and skiers in the winter.  It's overlooked by spectacular mountains and filled with quaint holiday apartments, Irish theme pubs and gift shops. My virtual version isn't quite so attractive. Things were going swimmingly until I built a one-way street in the wrong direction. Doing that meant bin lorries couldn't drive down it to pick up the rubbish. Garbage built up without me noticing and now everyone is dead. Lesson learned.

Cities: Skylines is all about screwing up, learning lessons and starting again. The original game has been around for six months now, with glowing reviews when it first arrived. Fans of city-building games were so utterly desperate for something that truly embodied the spirit of 2003's SimCity 4, and with the disappointment of 2013's SimCity reboot still fresh in the mind, the only way to go was up.

Half a year has passed, with the new After Dark expansion recently adding various new features. I've personally sunk more than 100 hours into the game in that time, and while that speaks volumes about the game before I even get into my review, things aren't quite so simple.

Gameplay

Like most city builders, you're given a blank piece of land to do with what you wish. There aren't any planning regulations or green belts to worry about; you just build what you want, where you want. Lay roads (two-lanes, four lanes, six lanes and highways), create zones for specific types of buildings (residential, commercial, industry and offices) and plop down services (schools, parks, hospitals, garbage, etc), and you have the barebones of a city.

From there, it's about expanding your city, dealing with issues as they arise. Most of your problems will be caused by traffic flow; sometimes it'll be down to your own lack of infrastructure knowledge (open up Google Maps and look at the design of streets in your local town to get an idea of how things work), but an awful lot of your traffic problems will be cause by idiotic AI behaviour. If the next turn a vehicle will make is a left-turn, it will sit in the left lane, even if that left turn is kilometers away. If that left turn is particularly popular, you'll find you have a huge traffic jam in one lane, with the rest of the lanes completely clear. To an extent this will be down to poor city design, but the lack of a lane editor (where adding a second left-turn lane would be extremely handy) means that these problems are impossible to solve without creating huge, looping overpasses that, while impressive, quickly turn every major intersection in your city into a colossal mess.

^ From high up or at street level, Cities Skylines looks great

Traffic jams cause huge problems for your services and citizens. Emergency vehicles get stuck in traffic with everybody else, as do garbage trucks and hearses, so the problems caused by vehicle behaviour aren't just cosmetic: they're game-breaking.

The addition of an optional day/night cycle in After Dark compounds these problems, revealing many shortcomings in the underlying game engine. Citizen behaviour only changes slightly at night, with buildings like schools still lit up even at the dead of night and students milling around in the playground. You can change how city services behave at night, for example shutting down some bus routes or only letting garbage trucks roam around in the daytime, but your citizens don't understand this and will complain when they see there aren't any bus routes near their home - even if it's night time and they don't need to go to work right now.

Leisure zones (new in After Dark), are more active at night, and taxis seem more popular, but aside from these very basic changes, little changes when the sun goes down. That's not to say the expansion isn't worth buying; it's just that you shouldn't expect it to completely change how you play the game.

Despite the myriad problems you'll face, it's incredibly easy to make more money than you know what to do with. Once you've set up all the basic services in your city and have a steadily growing population, it's extremely hard to go into debt unless you mismanage your city by, for example, building a huge underground train network that costs a huge amount and is underused. Aside from utter incompetence, you'll never have money problems.

It's a shame, because the game is absolutely beautiful. The developers have absolutely nailed the art style, creating truly epic landscapes and skylines from a distance but sticking with a slightly more cartoony style close up. Being able to divide your city into Districts, which you paint onto city, makes your city feel alive, and lets you create a narrative for your city with districts that have local by-laws that make them different to the rest of the city.

It makes the game a far better sandbox than a real city management sim. I now have the most fun playing the game with unlimited money and all buildings and services unlocked.

Modding

The developers obviously had some foresight when it came to their own shortcomings; the dev team, at last count, was just 11 people. In reality, it's several thousand, because Cities Skylines supports third-party mods via Steam's Workshop. There's an excellent list of the best ones available on the game's subreddit . I would not have sunk 100 hours into this game without them; many of the mods fix longtime problems with the game. Better public transport management, the ability to time traffic lights, assigning turning lanes, new buildings, even improved colour profiles are among the mods I use personally, but there are thousands more I'm yet to discover.

^ Your cities can be vast; this city takes up just one tile, with a maximum of 9 (or 81 with mods) available

Cities Skylines relies too heavily on these mods. Every update to the game is potentially mod-breaking, and hoping that the developers of the most popular mods will continue to develop them without payment is a big leap to make.

Cities Skylines is a gorgeous game, and After Dark only costs £11 - it's easily worth buying if you find yourself enjoying the main game. My main concern with the overall package is that, without mods, you'll grow tired and frustrated with the game's limitations after perhaps a dozen hours. For a game that doesn't cost a huge amount to begin with, perhaps it's not a huge issue, but if you're in it for the long haul, you should make yourself familiar with the various resources that list essential mods, and keep up-to-date with the latest changes. It takes more commitment than other game genres, but if you stay in tune with the community, you'll be rewarded with a gameplay experience that will continue for dozens of hours.