So at the moment you just get slots by popularity, use, money, rep etc. I would change the system so that you get slots on the base of bidding on them for a route you want to open up. This shall be decided by the amount of money bid with a percentage of luck. It should be dependent on the number of slots free in the airport, also the old factors and the load factor of the other routes from that airport/country. It shall also be negotiated how much the slots cost the airline per month in terms of a contract that can be renegotiated from time to time, so the airport gets more power.