Eh. The digging mechanic is cool. But the movement is a bit too quick and slippery for a mechanic that precise. As fun as I find it to speed through levels, a more firm grip on the ground would make things not so sudden, especially with the precise platforming challenges. Maybe also lower the overall speed a bit so the player is more certain of where they'll be. And I wish it was clearer from the start you could dig in front of you. Maybe an indicator of which block you would be digging depending on which direction you hold.
The sudden speed and uncertainty of which block you'll hit combine to make the final challenge all that more frustrating. There were several times where I was sure I hit the top block but missed, and several times where I did hit the block and was ready to charge forward to hit the blocks behind it... only to not land on the block and either land in a lower tunnel the game made me dig up or just straight up fall to my death.
And while I'm talking about the final challenge, I remember getting everything right on it and was super satisfied to jump on that final spring, but because I didn't know what was beyond that and I was still holding right, I fell onto a spike and had to do the challenge all over again. It was very disappointing and felt unfair to me.
Maybe when there's a moment like that, where you don't know what's beyond the end of the challenge and one wrong move after beating it the first time results in failure, maybe have some sort of safety net to ensure the player can move on from the challenge after passing the screen beyond the challenge. Like, using that last challenge for example, some sort of platform that you can phase through until you could land on it. Just so the player doesn't get punished immediately after beating a challenge like that.
I do like the digging mechanic, like I previously said. It makes for a fun puzzle platformer, especially when you have limited uses it. And the pixel art is very nice, especially on the stone tiles. The game has a nice aesthetic. Personally, I wish there was sound, but it did fine without it.
Overall, the game has a nice visual style and a cool dig mechanic, but it has a few minor flaws that can and do sometimes combine to make unfun situations. So, it's alright.