Suggest to make more new mission
I suggest 3 type
First type(the one we have at the beginning)
protect the stations,
one wave and one wave enemy come to attack, the last wave have a special captain plane and a large amount of usual enemy.
A Special huge Battleship arrived, every one minute send out five plane, the players need to destroy the battleship before it arrived the Destination.
The Special huge Battleship have a few part, each part have each effect, after destroy all of them,go to destroy the Core, then it end.
War of Two team of Battleship,Both team have some players.
They need to destroy all enemy Battleship.
The enemy captain player and two captain(computer) each of them protect by one team of plane.
each player can die 10 times.
If the captain player, then no new captain come out.But that player can continue to play.