I'm a big fan of Motherload which this seems to be based on, so it's a little disappointing that some of the the basics didn't translate through to here.
The game is extremely grindy, even when you dig straight down it takes forever to make progress, and weapon upgrades don't seem to make it any faster, just lets you dig a little longer before having to go restock.
The theme works alright, but it's kind of at odds with the rest of the game. Mining takes such a long time as is, the recoil thing makes it worse since you can't just spam easily. There's nothing really to avoid, nothing specific you need to aim at, and you don't take fall damage, so there's very little reason for the mechanic to exist. If mining was faster and the ground was scattered with unbreakable obstacles and dangerous hazards, then the recoil mechanic would start to make more sense. Imagine navigating through corridors and mining ores while trying to avoid shooting at a TNT by accident or falling to lava.