Full Bore

Here's an excerpt from Full Bore's Steam description:

Deep underground lies a reminder of Boarkind’s darkest hours. All it takes is one little boar to dig it back up.

Harkening back to the NES era, Full Bore is an open-world puzzle game that leaves you to your own devices. With curiosity as your only guide, you will figure out how the blocks around you behave, delve deeper into a strange underground, and eventually piece together the story of a world transfigured.

Full Bore debuts a unique lighting engine that creates rich, atmospheric environments out of its old-school pixel art. Combined with our original bluesy soundtrack, you will soon find yourself immersed in Full Bore's mines, temples, scrapyards, lava tubes, inexplicable lakes and/or mysterious laboratories.

With over 150 areas, no single intended path and secrets everywhere, Full Bore gives you a world in which you can always find something new (until you find everything)