Oddworld: Soulstorm Enhanced Edition

This can be easily earned on level 5 - 5. Sorrow Valley

Early on in the level, after meeting your first flying Sligs and climbing a large ladder you will come to a split on the path, with an upper and lower level. On the lower level you’ll see a green lever - take the upper path to a cave.

I think you have to come to this cave to get gas to progress the level - but I haven’t managed to complete this part yet

Inside the cave, climb up to find 2 Mudokons by a sleeping Slog. Quietly heal at least 1 of them and drop back to the ground where you came in. To the right you’ll see a door with a fire and 2 more Mudokons.

Climb up above this with the first Mudokon following you, telling them to wait on the switch to the left, opening the door below. Run inside to the other sealed door, this should wake a Slog on the other side. Now just hang around and your achvt should pop!