It's incredibly easy to love almost everything about this quirky platform-adventure, right up to where you've mined every possible direction and are starting to feel a little bit lost. But, that's just when SteamWorld Dig 2 turns into a different sort of a game: It shifts from haphazard carefree exploration to careful study and inspection. Unlike its predecessor, SteamWorld Dig 2 has a persistent world; the original had randomly generated caves. Here, there's much more care into imparting a specific type of experience to the player, with the world and overall play experience benefiting from it. The general flow of the game stays the same as before, since you must constantly return to the surface to trade gems and restore your energy stores -- which, yes, sounds like it could be boring and repetitive. In fact, it winds up being strangely addicting because the deeper you dig, the more you're forced to gamble on whether you can survive on your way back (to potentially upgrade your abilities) or whether you should press on (to see what sort of upgrades you might need). People typically call games like these "grindy," in that you have to put in your time grinding away to "level up" and earn new abilities to really make progress -- but here you're given so much freedom that you really are the maker of your own digging destiny.
It also helps that there isn't just one shaft to explore. There are other areas that, once you get certain items and understand how to best use them, you'll realize you had blown by in the very beginning of the game or that you didn't even realize you could go to. But, no matter where you go and what you do, this is a game all about digging. It's all about the loop of exploring, harvesting, and upgrading. All in, you can expect about 15 hours of this loop -- especially if you're trying to collect every single item and upgrade everything completely. That, in turn, unlocks a bonus dungeon, all of which means the developers paid attention to complaints that the first game was great but simply too short. This one will keep you busy for a while, but because of its singular focus, it means either you'll like all the mining and risk-reward calculations you'll be doing all the time, or you'll just not get it. The latter is unlikely, because this is a simple and straightforward game that's fortunately also a lot of fun.