I’m so sorry to hear that. We are grateful that you tried it. Are you sure that miner was powered ?
Oh, I figured it out now. Awesome game mechanics and graphics! As it is a tower defense game, perhaps there could be some walls or barricades?
I also experienced the 1000 limit with the materials as another comment mentioned.
I couldn't recognise that cube was metal. I thought it was land. Perhaps a hexagonal shape would be better.