Up until lvl 9 I was unable to kill all of the ships flying at me, got all the way to 9 lives left. however once I maxed out the firing speed it became quite easy. Made it to lvl 15 without a ship getting closer than half way. how ever once i upgraded the movement speed past 100 the ship was moving faster than the bullets could be fired (since firing speed maxes out around 25) I ended up dying because of that which is frustrating. Final upgrades: movement speed = 315 damage = 200 mining = 200 weapons = max firing speed = max. The game needs a lot of rebalancing. Over all not a bad concept just needs to be tweaked.