Oddworld: New 'n' Tasty

There is only one spot in the game where you get the chance to kill 30 slog's and that's the last room of Zulag 4.

Take control of the Slig and pull the first lever. Shoot all the Slog in Bursts and go to the lever nearby. Quickly run to the right and turn around to shoot the Slog's that come out of 2 doors. Watch out because the door on the right holds less enemies and some will still spawn from the left.