Oddworld: Soulstorm

You only encounter Sleeches in Level 13: The Sanctum, which are worm-like creatures that can kill you almost instantly. Luckily, they don't like light. Unlucky for you, you're deep underground, but lucky you there are ways to light up! Early in the level you will find a torch you can use and if you search all areas, lockers and bins you can find flares. Flares are much better for protection as you automatically hold one whilst running and jumping, whilst the torch you can only hold in one direction and its power will drain with persistent use.

If it's safe to do so, use the torch on every group of Sleeches you see, otherwise use flares. Both count towards this trophy and there are more than enough Sleeches to go around.