I know that is another topic but guys.
Higher and more advanced tiers should have more slots. This is understandable when we are not well advanced. However, this should change during our development.
Just think. A situation in which you produce supercomputers, turbomotors, atomic energy, but you can't wear a gas mask and shoes at the same time? :) The constant change between shoes and jetpack is frustrating.
What will happen when you are in the radioactive zone where you will have to fly to the poisoned place ??This is a fairly radical example, but there are many situations in this type of game.