i would say its a great idea and frame work and i can see it going far if you allow it to personally i would add that $ per min or $per sec mechanic and maybe add a bit more graphic maybe add the use of tnt and different types of units besides miners
it need to give you a amount that u make per second or minute on the screen so u can see how much u are making like a score and it helps you figure out when u will have the money to buy what u need i highly recommend you add it
Its supposed to be finished in one sitting, what can you do. Saving is impossible to do in scratch.