Oh wow is this really your first gamejam game? You were really ambitious and the crazy thing is, you set out to do most of what you had accomplished! The controls feel fun and responsive, even if I find using UP key to jump a bit awkward, but they were really great otherwise.
I did find that if I pressed the mining button in certain areas the game would slow down or crash and I'd have to restart, but that was rare and I eventually learned to just not - mine against the ground or walls.
This is very polished work for a first release. great job!