Above the game is left has UPGRADES, when massacres
the certain quantity the enemy can increase family XP, then may
promote the related skill in UPGRADES, the skill comparison explained:
RELOAD: The filling ammunition time speeds up RAZOR
ROTORS: Increase flight speed and skill GUN AIMING: Runs
aiming increase adrenaline: Strengthens character''''s attack speed
stunting: Growth value cluster bomb: Increase bomb power
armor. : The armor increases spare planes: Increases
the spare equipment The game needs two people to coordinate to
play together, selects right side the picture 2 player button start,
it slights the law: P1:W, A, S, Dcontrol migration,
G/ to place bomb, F/ 跟追 missile, P2: Mouse/machine gun fire,
above-below direction key.