Oddworld: Stranger's Wrath HD

Story-related. Cannot be missed.
The first order of business is to kill the Giant Sleg so you can learn a Sleg call to lure out Lefty. Head left along the Mongo River (through the Port Authority) and you will encounter the Giant Sleg, as well as a couple of regular ones. Stay on the other side of the river and the Slegs won’t be able to bite you, but the Giant Sleg will have a spit attack that you need to watch out for. Use Stingbees, Fuzzles and Boombats, anything to kill the Slegs, and then head back to town to learn the Sleg call.

You will encounter Lefty in a Native graveyard, on a perch with some Snipers in the area and some Outlaws on the ground. Run to the far right for cover near some tall grass and ammo. Take out the Outlaws as you have been doing in the game so far. Lefty will send out at least two more waves of Outlaws against you and will occasionally shoot at you himself from the many perches he will occupy. Eventually he will come down to ground level, where you can fire Zappflies and Thudslugs to bring him down alive.