As Image & Form often reminds us, its now-familiar core IP began with SteamWorld: Tower Defense on DSiWare, a thoroughly decent tower defence game. It was SteamWorld Dig that was transformative for the studio, however, achieving well-earned success on the 3DS and a range of other platforms. That allowed the team to up the ante in terms of technology and ambition with turn-based play in SteamWorld Heist, further establishing the company's reputation. Now we come back around to the game that was second in the series but really started it all, with a fully fledged sequel in the form of SteamWorld Dig 2.

Upon booting up the game and starting the story it's immediately apparent that Image & Form has never been so confident in its own qualities; the look that's graced the series since the original Dig has become refined and eye catching, with the visuals being undeniably striking. We started off with the system docked and the game looks terrific, with environments being heavily stylised. Switching to the portable mode the game still shines visually; in fact, we were drawn to handheld play on a regular basis during our playthrough.

Early on players learn the basics through carefully choreographed albeit hands-off tutorial areas. You're guided to specific points, earn new abilities and even have an early boss encounter; this battle sets the tone and brings some fantastical colour to proceedings. Playing as Dorothy, you quickly learn that she's on the hunt for Rusty following the events of Dig 1, and teams up with a floating light-based being with a name familiar to fans of Heist and its Outsider DLC. The game is full of references to lore - we found ourselves piecing it together as we played - and the game also has a cute way of recounting the basic events of Dig.

Pretty soon you meet a new cast of quirky bot characters and you get into the nitty gritty - digging and exploring. The term 'Metroidvania' certainly does apply, as your chances of reaching new areas are restricted by a mix of gear and mysterious abilities that Dorothy inherits from machines scattered through the world. Early on you discover simple and familiar things like dashing, but later you get goodies like a hookshot and 'jackhammer', a powerful ability to bash through previously impenetrable rock. Dig 2 goes further in its abilities that its predecessor, with some pleasing surprises the further you progress that also play into nice puzzle and exploration elements.

The core loop remains, too - you dig not only to explore and carry out objectives, but to accumulate wealth. Blocks with minerals and ores are clearly marked, and by mining these and taking them to the surface you make money that you can then invest in improvements to your toolset. As always digging has a bit of engineering nous to it, as you work around (or towards) enemies, and try to ensure that you dig in such a way that you can easily retrace your steps back to a checkpoint. There are pipes that serve as warp points, too, so you can plan your tunnelling around managing smaller areas between these fast-travel resources.

Once you return to the surface it's all a balancing act as you consider how to spend your money - expand your bag to carry more minerals, strengthen the ever important pickaxe? Minerals are finite - though there's no major shortage - so the fear of dying is also ever-present; if you die you lose some or all of your collected resources, though your stack of cash goes untouched.

An addition here are upgrade cogs that you find, often within challenge rooms scattered around the world. These challenges are a nice diversion, often riffing on a recently discovered ability, and the cogs themselves can be used to add special abilities to your various tools and gadgets. It's all very well balanced - as you acquire wealth and improve your gear more abilities are available, and you find cogs to make the upgrades. You can also move these cogs around as you please, so when heading to an area with lava, for example, you can give up a couple of abilities elsewhere to free up enough cogs to increase your resistance to dangerous terrain.

As is now typical of Image & Form games it's carefully constructed and works beautifully in practice. The mechanics make the process of digging, exploring and progressing the story feel entirely natural, at least in our case. That's just as well, too, as it's a sizeable world we're dealing with. Initially it feels like the original in size, but then the story and scope expands and you gradually stretch into dark areas of the sizeable map. There's nice variety in environments, too, with different types of enemies and terrains to explore.

While the first game's story was relatively light in scope, leaving you to piece it together yourself for the most part, there's a bigger narrative here to match the sizeable world. There are some interesting interactions and twists, though its finale is easily guessed a good while before you get there. Structurally it's pretty standard stuff - revisit old areas but dig deeper to find important items, for example - but it's entertaining, especially with all the dangnabbit-style Steambot talk.

Players can also choose how much help they want; in the interests of brevity we kept the game's full map system, which generally points you in the right direction for the current objective. This makes sense when there are multiple segments to the sizeable world, but some seeking a greater challenge may want to turn these off for a longer, more detailed playthrough. For our part we saw the credits with our save file clocking our run at around 6.5 hours, but the statistics showed that - despite finding the core abilities - we'd only found about a third of the 'Secrets', including collectable bits-and-bobs that you trade for upgrade blueprints. We only got a silver rank for that time, too, so the idea is clearly to encourage everyone into speedruns.

We have little doubt we will revisit it, too, as it's an enjoyable ride while it lasts. Though the overall story is easy to predict it does fit into the series lore very well, and the interactions between Dorothy and her ethereal friend are particularly entertaining. There's one scripted segment - that we won't spoil in detail - that really stands out too, sweeping you into a highly mechanised and creepy sci-fi environment. In fact, that part was that little bit too short, a fun idea that could have been used more. We were certainly left wanting more when it ended; that's a sign of the game's quality, and a reminder that there are limits to what small studios can do even with the most ambitious of ideas. The credits were eye-opening in showing the modest size of the team that produced such an impressive game.

As for where SteamWorld Dig 2 stands in the current indie scene, after its predecessor rocked the boat in 2013? It's among the elite Switch eShop games, and certainly stacks up well within the broader Indie world. It's of a similar level to Heist, too, in that it's the highly polished, quality work of a studio that's clearly on a roll. It's also another terrific arrival for the Switch, especially as it looks so handsome in the portable configuration. We tended to prefer the 3DS versions of Dig and Heist, as they felt like they belonged on the system. On Switch you get the best of both worlds, as you can enjoy the HD experience either way, and it's games like Dig 2 that highlight the console's concept the best.

Conclusion

SteamWorld Dig 2 is another confident effort from Image & Form, and a worthy successor to a game that's a treasured part of many eShop collections. Stylish and good-looking, it also has the series' trademark humour and, yes, a pretty good soundtrack. It refines and expands upon the qualities of the original and hits some delicious high points, albeit some of the smartest segments and ideas appear only briefly. It sets the scene for more content and games, too, which is pleasing to see.

For fans of SteamWorld Dig we suspect the recommendation isn't needed as they'll buy this anyway. For those that skipped the first game, however, Dig 2 is a must-have - its charming aesthetic and cast set the scene for a tightly designed and clever exploration game. Now the wait begins for SteamWorld Dig 3.