The old gods are dead, humanity lives uneasily alongside a race of horned giants, there's a long dormant race of walking suits of armour on the rampage, and the sun is stuck in the sky.

As premises go, The Banner Saga's is a little different from your average tactical RPG.

But that doesn't cover the half of it. This is one of the freshest games of its kind - or of any kind for that matter - to have hit iOS in recent times.

Inspector norse

The thing that appealed to me most about The Banner Saga's setting is that it eschews the usual steampunk JRPG or western Tolkienesque fantasy influence in favour of a universe inspired by norse mythology.

The fiction here is thoroughly engrossing, with believable characters who talk to one another like they're real human beings - even the ones who are 12 feet tall and live for hundreds of years.

It's a pretty grim tale, though. The returning Dredge are cutting a swathe across the world, pushing already strained alliances to breaking point. Added to the sun throwing a paddy, there's a deeply foreboding end-of-the-world feeling in the air, which brings out the worst in many of the people you meet.

But it's all softened by a simply gorgeous cartoon art style that makes us think of old Disney films from the '50s and '60s. As your motley crew makes its way from ravaged town to bustling city to bleak wilderness, the view pans out to a side-on portrayal of their journey, highlighting the scale of this land.

A song of ice and... more ice

All of this, and we haven't even mentioned The Banner Saga's gameplay yet. Don't worry, as while storytelling and universe building is the true triumph here, The Banner Saga plays beautifully too.

The main part of the game plays out as a kind of interactive choose-your-own-adventure tale, complete with multiple choice sections that affect the path of the narrative. These succeed simply because the story is so interesting and well told.

The decisions you find yourself making as the leaders of various clans are never as easy as simple right and wrong, and there can be dire consequences for even a seemingly noble act.

As you traipse from point to point, there's a light management element that sees you eking out provisions, deciding where to spend the game's single versatile Renown currency, and mulling over whether to accept more followers to your cause (more people means more fighters, but also more mouths to feed and more potential for internal strife).

Pillage people

The other major part of The Banner Saga is its battle system. This takes the form of relatively small-scale isometric turn-based scuffles, but it's sufficiently different from other tactical RPGs out there.

The system hinges on the two gauges that each combatant has - strength and armour. Strength represents both your hit points and your attack power, so taking a chunk out of an opponent's health also weakens their ability to strike back.

However, attack an opponent with a high armour rating and you'll barely make a scratch, with every chance that your blow will glance off harmlessly.

This makes battles an intriguing balancing act between chipping away at your opponent's defence and going for the jugular.

You'll also need to make tough decisions about which characters to take into battle with those that have fallen in previous fights starting the next with a strength penalty, unless you give them sufficient time to recover.

Ebb and flow of battle

There's so much more to discuss about The Banner Saga, such as its memorable soundtrack, it's nuanced character classes, and its sparing but effective use of voice acting (in suitably scandinavian accents) - but all you really need to know is that it's a truly top class game.

It's not quite a perfect iOS game, though. This is actually a conversion of a PC game, and the transition to touchscreen controls hasn't quite been as successful as we would have liked.

The grid-based battle sections in particular suffer from frequently sticky, unresponsive square-selections, and slightly cluttered battle menus.

The view here regularly feels too zoomed in, with too much of the action seemingly occurring on the very edge of the screen - or even just off it - and that's playing through on a full-sized iPad.

I should also note that performance was a little stuttery on my iPad 3, and that the loading times were a little long - but then my machine is getting on a bit now.

Such matters can be forgiven for the most part though, because The Banner Saga is a truly memorable experience - even if you don't typically like tactical RPGs or gamebooks.

It's unforgiving in certain ways, deeply unusual in others, and it requires a little patience before it really all soaks in. But when it does - and it will - you'll find one of the most richly rewarding iOS games of this or any year.