The two hottest properties in indie gaming right now are Sweden and spelunking. From Amnesia to Hotline Miami to Goat Simulator to that DotA song, a hugely disproportionate number of big independent releases the last few years have come from Swedes; whether it's Cave Story, Shovel Knight, The Cave, or Spelunky, we've also seen a renaissance of titles about digging and caverns. The synergy of Sweden and spelunking has even come together for a few big Swedish games about spelunking, like Knytt Underground and perhaps this decade's biggest indie game: Minecraft. Of course.

So it comes as no surprise that Gothenburg-based studio Image & Form's subterranean adventure, SteamWorld Dig, is absolutely fantastic. After hitting the 3DS eShop last year to roaring critical and commercial success, it's Wii U's turn to get in on the Dig Dug-meets-Metroid action. You play as a robot named Rusty, with a voice like a goofy unintelligible Transformer, who arrives in the tiny town of Tumbleton to claim his mysteriously disappeared uncle Joe's goldmine. After finding Joe's rusting remains with a surprisingly nonchalant reaction (they're robots after all, we suppose), Rusty plunders his uncle's body for his pickaxe and takes off on a steampunk digging extravaganza.

SteamWorld Dig risks getting lost in the over-saturated shuffle of endless steampunk indie games, but the unique aesthetic manages to stand out. If you couldn't tell from the game's subtitle — A Fistful of Dirt — SteamWorld wears its spaghetti western influences on its sleeve; the memorable soundtrack is a fittingly haunting mix of Ennio Morricone-influenced tracks with tinges of electronica, all with a heaping dose of reverb to reflect the acoustics of the underground caverns you're exploring. The cartoony art style is fairly unremarkable, but the meticulous attention to detailed animations makes the characters come alive, and the sweeping western colour palette of oranges and browns gives a distinctive feel to the game world.

The basic gameplay loop of SteamWorld Dig consists of exploring a vast mine to harvest minerals that you sell to the general store above-ground so you can purchase upgrades. All the mines are procedurally-generated, which means no two playthroughs will be alike; procedural games risk getting repetitive, but SteamWorld's mechanics are rewarding enough that you'll want to keep coming back for more. There is some basic combat against cave-dwelling foes, but SteamWorld's focus is squarely on exploration and puzzle-solving, so for the most part it's a relaxing, stress-free adventure. The controls themselves are intuitive and reliable: rather than toy with touchscreen shenanigans, you control Rusty with the left analogue stick and face buttons.

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There's not much to do at the beginning of your adventure aside from swing your pickaxe to dig deeper and defeat enemies, but the developers have found so many unique uses for this simple set-up that it never gets old; new items and mechanics are slowly introduced, but it's never overwhelming. You have to keep track of how much light you have left in your lantern, and there's a constant cycle of digging just deep enough that you have time to return aboveground to refuel. This backtracking lets you re-evaluate areas you've been through before with your new items — in a Metroidvania style — but teleporters and shortcuts keep it from feeling like a slog. Since Rusty is a steam-powered 'bot, you also keep track of your water level, which lets you use steam-powered drills and high jumps – these abilities are useful for navigating the world, but if you run out of water completely you'll still have your trusty pickaxe and basic jumping ability to get you through until you can find more.

This is essentially the same game that appeared on 3DS, so most of our thoughts from our review of that version will apply here as well, but there are a few obvious upgrades: the gorgeous HD visuals look crisp on the GamePad, and they absolutely pop if you've got a nice flatscreen TV to play on. While many developers seem to struggle with how to adapt their controls to Wii U without feeling gimmicky, Image & Form completely understands the console – on default settings the gameplay is displayed on the television screen (uncluttered by UI elements) while your map and menus are down on the GamePad. You can easily switch to off-TV play with a touch of the Select button; far too many Wii U titles either display the exact same content on both screens, or ignore the GamePad screen altogether. To hit this one out of the park, SteamWorld also supports the Wii U Pro Controller.

Conclusion

At a relatively low price point, Image & Form's SteamWorld Dig provides nearly endless hours of spelunking fun – it even keeps track of how many metres you've dug altogether so you can marvel at how much of your life you've wasted away caving deeper. You've seen most of the elements of SteamWorld in other games, but very few titles bring them all together with such a high level of polish and focus, and a simple gameplay loop that will keep you coming back for more. With tight controls, a lush Western soundtrack, and beautifully animated sprites, SteamWorld Dig is one of this year's best games on the Wii U eShop, joining Ittle Dew in the "gorgeous Swedish indie adventures" category.