The Mechs are robotic Bipeds created by Mech Morphix. They have a gun mounted at the top and are arguably the most dangerous common enemies in Duke Nukem: Manhattan Project due to their immense firepower. All three variants lack close combat capabilities but can be hard to approach.
Mech lvl 1
The first time you'll see a Mech will be on part 2 of Chapter 5 "Fearsome Factory". It basically looks like a gun mounted on two robotic legs. It will detect you once you enter its range and the little green light that surrounds it will turn red indicating it has gone into alert status which is a good way of knowing if it has deteced you or not. While it is in its alert status it will continue firing shots and moving towards you until you kill it or until you die.This Mech's shot does 25 damage to you but the good thing is, it doesn't have a close range attack nor can it attack you if you crouch.This makes fighting it easier considering all you have to do is duck and shoot it. Kicking him to death isn't so hard either because all you need to do is duck under his initial shot and get close and kick him. Of course it takes more than one kick to put it down but as long as you remember to crouch between his shots you should be fine because if you don't you'll be killed quite easily. Killing any Mech with your boot also provides a nice boost to you ego so remember to do your best to kill a Mech with your kick if you're low on health but be careful as timing is quite important. One of the safest and easiest ways to kill a Mech is with the Pulse Cannon.
Mech lvl 2
This variant is a little bigger and stronger than the lvl 1 version, and also has a somewhat green tint to distinguish it from other Mechs. Much like the lvl 1 Mech, this one attacks by shooting you as well but with a minor change.Instead of just one shot each time, it shoots 3 straight shots each time which take out 5 ego points each. While it's true that that's less than how much damage the lvl 1 Mech does, the lvl 2 Mech takes longer to kill due to the fact that it's more durable and thus would have more time to inflict damage on you. However it can be killed in the same way as the lvl 1 Mech. Like the Lvl 1 Mech it also has a green light that turns red when in alert mode. http://i702.photobucket.com/albums/ww28/Jhin-Roh/Duke%20Nukem%20MP/Droid4.jpg
Mech lvl 3
The 3rd variant of the Mech is the strongest regular enemy you'll meet throughout the entire game. You can recognize it by the rather big metal slotted hood it has mounted on top of its gun. Fortunately, due to the fact that it's a Mech you can kill it just like you kill the other Mechs, however this one has a second method of attacking. In addition to the regular shot it takes at you now and then which does 40 damage, it can also shoot a cluster of pipebombs at you if there's a slight distance between you and it. As opposed to the shot it fires at you which you can duck to avoid, if you duck and it shoots that cluster of three pipebombs at you, you'll be hit. You must jump in order to avoid the pipebombs attack. Although each pipebomb deals only 5 points of damage, it's recommended that you avoid it anyway, because there's always a chance you'll get hit again, this time even by the gun shot. The best stragety with this Mech is to just get close to him, let him fire, and then kick him and repeat the process until he's down, which will get you a good 50 ego point bonus.Like the Lvl 1 Mech and Lvl 2 Mech it also has a green light that turns red when in alert mode.