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.