Version: Alpha 6
Bug: Performance issue
This one is related to performance! As I now have 4 mining rods, if I don't collect them, the game starts to lose fps!
One thing i think you should do @HopFrog, is deactivate the renderer of the object that is not inside the camera! I don't know if you do this, but as i saw your concept of map, you'll have a big issue with performance since there is an random spawn of objects (Trees, rocks, etc) over time, and the player will be navigating through the map while the rods will be mining, but not collecting them. Deactivanting animations, renderer letting only the logic information of the object remain on that coordinate, will increase performance!
Another idea is to give a despawn time for every collectable item. this way you'll keep the gargabe in-game clean and the memory usage pretty well.