My criticism might feel a little harsh, but I'll give you the advice you asked for!
It *is* very repetitive. It would be interesting if something changed every loop, like if your tunnels persisted. It reminded me a lot of Motherlode, and I think that making the ability to move left and right more impactful--like mining sideways--would add a lot. For game jams specifically, most people aren't going to play your game for more than a few minutes so it's important to give them interesting stuff to do right off of the bat. The upgrades are priced a little high, the loop timer is a little low, and it feels like a lot of clicking for little reward. Adding an autoclicker would save a lot of people's wrists and let people explore the game more.
That being said, making games is hard and this is still a good attempt! Great job submitting, and hope you feel better soon <3
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Thank you so much for the advice, it means a lot, i had an idea to have the player mine sideways but that plan fell down the drain once i got sick and couldn't get 3 lines of code correct :/ , but the game is the game so thank you for playing my game and for making time to comment and give me such an advice, it wasn't harsh and it will be quite usefull in my next project so thank you again, also thank you for your kind wishes! <3