The Hummer is robot that hovers above the player and fires explosive missiles from above. They have a significant amount of health, which can prove annoying in earlier levels where stronger weapons may not be yet available.
Attack Hummers have a somewhat more planned out attack strategy, if you would. Rather than hurtling themselves straight at the player in an attempt to overwhelm them, they keep to the skies, firing red bullets at the player from above. Their form of attack, and there continues movement back and forth can make Hummers much, much harder to target and take down, especially if the player is using a gun with low accuracy or a single shot firing mode.
Hummers use missiles that cannot be deflected by the player and cause massive splash damage to anyone unlucky enough to be caught in the blast radius, often draining the health bar by a third. Try to dodge or shoot down these missiles wherever possible and always keep moving to prevent being struck multiple times.
Hummers will never move in to melee the player and they will never intentionally come within range of being hit by the player. This can make confrontations with other robots much more difficult, especially when your dodging multiple projectiles from above and ground level.
Hummers frequently move from position to position, for this reason an automatic weapon or one that firs explosive projectiles would be preferable. Try to avoid close range or single shot weapons such as Shotguns and Sniper Rifles, as these types of weapons can make getting a shot on a moving target more difficult.
Players should consider jumping into the air before shooting at Hummers; this will decrease the distance between the player and the Hummer, therefore increasing weapon damage or the chance of a weapon hitting its mark.