Metro 2033

This is about the last level you will go to, called "D6" its towards the end of the level also, so when you are told to go down to the lower levels, after the electricity goes out in the computer room. As soon as you walk out of the door, there will be two amoebas. Thats just the start of them, then one guy says he will protect the room. Keep going to the elevator. (You will have one guy with you, Miller) Now, when you get off the elevator, this is where you should get the achievement. There is pods everywhere, once you get close to them, they will produce one of these slimy looking amoebas, kill them, but also protect Miller. You can shoot the producing pods to stop them from coming by the way.

At the level D6 of Chapter 6 you will go down to the lower level to
start a generator, therefor you'll have to fight your way to an
elevator. On your way to this elevator you will encounter the
Amoebas, Amoebas are ball shaped creatures; they look like gel
with brains ;)

Shoot five of these gel-brains ;) and the Achievement is yours.

Another game-play tip for this level: shoot the emerge-holes where
the Amoeba(s) came from. This is the only way for you and your
friend to survive this section.

Have fun Hunting Achievo's