War Machine

From the publisher:

War Machine combines economics, trade, diplomacy and elements of land, air and sea power into an easy to play game. The object is to gain control of the three major cities on each of your opponent's boards. It takes some luck and a great deal of skill. Strategy depends on you alliances and whether you have a Land, Sea or Air Nation. Each Nation has an advantage in either land, sea or air capability. Deciding what to produce, where to deploy and when to attack will determine your success or failure. You can become an effective player after one game and a master player after only a few games. War Machine is designed for two to three players, but can be expanded to four players by borrowing a board from a second game.