At its heart, Airlines Europe is a stock game, with players earning points for the stock they hold in particular airline companies when one of the randomly determined scorings takes place. On a player's turn, that player either expands an airline and claims a stock, plays a stock onto the game and receives dividend, invests in a special airline called Air ABACUS, or gets a certain amount of money from the bank. A player scores only for stock in play, bu the value of an airline is determined by the value of the route licences that airline owns - thus, you're torn in terms of what to play when.
(Source: Boardgamegeek.com)