Eat Lead: The Return of Matt Hazard

Start a game on easy (or normal)...then consecutively you have to kill 5 enemies in a row without dying by only melee. Run up to an enemy and hit 'X' 3 times to kill an enemy. If you see a big group of enemies...pick them off one at a time. Try to manuever around to where the others cant see you and pick them off. Also, if you're getting shot, hide behind cover and rebuild your health and then go kill another one after that.

Also to note, you can be killed while meleeing an enemy, so be careful of that as well. You have to do this 5 in a row without shooting anyone else.

I received this achievement at the start of the butcher shop (second level) There are 5+ enemies. I just ran up to each one and hit the "x" button 3 times to melee them and the achievement unlocked. You can not shoot or die or you must start over.... Have fun!!

I actually got this achievement at the very end of the game. In the first of the three stages of the Boss Battle with Willy, you have the "Fembots" and Zombies. Take cover and head shot the zombies until the stop spawning. Then you have 6 or 8 "Fembots" to kill. Just head shot them to stun and then run up and melee. Do this 5 times and the achievement is yours. If you haven't gotten it yet, this will also give you 5 of your 10 1-hit melee kills. Hope this helps.

I got this achievement during Level 4, Backdoor Assault at the Big House.

After clearing the Guest house of all enemies, you will run up some stairs to continue the mission and eventually enter a tennis court area. This is where the game first introduces you to Zombies.

Numerous Zombies will spawn as well as 3 Russian soldiers. Kill the gun-wielding Russian soldiers and run to the centre of the tennis court to collect the Hazard pickup.

Now all you have to do is run up to each Zombie, one at a time, and press X to instantly kill them. Repeat 4 more times for the achievement to unlock.

I also used this method to unlock the Eat FIST! achievement.

Please comment if you vote negatively. I will edit my solution to make it better.