Mining Simulator 2014
Well, this is a disappointment. SteamWorld Dig comes out swinging with an enchanting art style and simple platforming mechanics, and some exploratory digging mixed in for good measure; the stage is set, here, for some kind of Metroid/Red Faction hybrid, set in a bizarre steampunk wild west. It seems like an insanely creative idea on all sides.
But that font of creativity slows to a trickle after only a few minutes. Your first pickaxe upgrade allows you to mine denser material; the second merely allows you to mine faster. So does the third, and the fourth, and (I think?) the fifth, or whatever the last one I got was. You find new abilities, very slowly, that make little to no difference in the moment-to-moment gameplay. You gather minerals, worth money, that you can slowly accumulate for minor upgrades. And you get those upgrades (and replenish your light source) by regularly returning to the surface -- meaning that you'll have to frequently interrupt your dig to climb all* the way back up to the surface.
* Or, at least some of the way. There appear to be teleport-checkpoints that limit how much you have to climb. But this limit is still way too much.
Digging is the primary focus of the game. You have to dig down, to find plot-relevant caves with upgrade-things in them, and to find better minerals for more money for new upgrades. In theory it's a fine progression mechanism, but the amount of digging you have to do to get anywhere is just too much. And the tedium around the digging - climbing back up, turning in minerals, descending back down, over, and over, and over again - is dull.
It may well be that later parts of the game are more exciting. But that's my whole problem with SteamWorld Dig: it seems utterly ignorant of how boring the general gameplay surrounding its key features is. Repeatedly digging holes and jumping out of them, is not, in itself, a fun time.
Better than: Blocks That Matter
Not as good as: Minecraft: Java Edition
Probably not as good as: Terraria, unless you don't have any friends, in which case it might be pretty close.
Progress: Didn't quite get to the third "cave."