Melee all day! Achievement
Melee all day!10
Perform a melee kill while you're in Overkill
To get into Overkill, you will need to kill enemies until your Overkill meter on the right hand side fills up. Then you need to press and you will go into Overkill, where you will become invincible for a short time. While you're in this mode, you need to run up to an enemy and press and you will melee kill them, violently, unlocking the achievement.