Wonderful game, it's impressive that you could do that in a week! I love how the oxygen pipes work, and it feels like the oxygen decay is tuned just right. The process of searching for more ores in the dark is fun, but doing it while managing the oxygen and the worms, it's very entertaining.
About the things that could be improved : pausing the game while the shop is open would make the player's life a lot easier, and having the shops be actually visible like the first town would help a lot. Also it wasn't clear at first that i could scroll down in the shop, which is too bad since vision distance, jet speed and ore yield seem like the most powerful upgrades. Also it's not clear that the worms can be killed, i spent my time just avoiding them lol.
Overall this gives me the same feeling as those cool flash games that would hook me up for hours as a kid, which is very nice. Once again, congrats on making such a game in just a week