SteamWorld Dig

SteamWorld Dig has a classic arcade game feel.  You are a small robot that is left an inheritance of a mine beneath a small western robot city.

Mining materials can be sold on the surface to purchase mining supplies and you can find upgrades within puzzle type caves as well.   It's fairly quick paced play but more fun than I imagined when just starting.

There is incentive to keep going -- your pack gets full of gems, so you unload them and upgrade something like an upgraded pickaxe, which is inspiration to then go collect another pack full of treasure.  The full game took about 3 hours - with only one boss fight.