Amazing game!! I also spent well over an hour with this, very enjoyable. Really like the building system, the graphics, and the sound effects while digging are veeery satisfying. Got so close to the end, but that last magma rock is strong as hell. I'll definitely come back for another run though! Fantastic job!
Edit: And I've only now found out how the pistons work, which adds a whole other layer to the building. Excellent!