I, Zombie

Very easy achievement. Just turn 10 soldiers into zombies. The soldiers are obviously the ones that can kill you, with the guns and helmets. It's easier to have your zombies do this for you, especially if the soldiers are in pairs because if you try to attack by yourself, you will be annihilated almost immediately. This is also cumulative and also doesn't have to be done in all different levels. you can change a soldier into a zombie, die, then repeat 9 times if you wanted to but the game is pretty easy and you will get this pretty early on in the levels. Once the 10th is turned into a zombie, bleep bloop.