I'm so glad to hear you enjoyed the game, There will be speed upgrades once I get to update the game I'm just waiting for the Game Jam to end. The second drill upgrade allows you to drill the Sapphire (dark blue ore) and Ruby (dark red ore) ores which you can't with just the second level of the drill you need the third. I might be adding elevators cause the depth will become much bigger later on. Thank you for playing and leaving a comment it means a lot to me!