Sin: The Movie

another cop drama with good action.  

Strait Jacket and Sin: The Movie are both OVA series that contain professionals who kill horrfying mutants. They are both extremely violent. 

Sin seems like one of those pieces of entertainment media inspired by the world and aesthetic of Blade Runner. There's quite a high degree of similarity between a "blade runner", aka a cop who hunts down bioengineered humans called replicants, and John Blade, a cop who hunts down humans bioengineered into monsters, both in neon-lit, corporate-controlled, cyberpunk metropolises. Both anime are action-packed and have similar vibes, so it's worth checking them out if you're a fan of this kind of style. 

enhanced villians, a lot of shooting going on, both have the looking for ímmortality´ as an ambitious storyline, not too complex, just enjoyable, and i like it ok, THERE U HAVE IT! :) 

Sin: The Movie and Halo Legends are both based on First-person shooter (FPS) video games from the US. They are both action-packed anime with a lot of gun action and feature the main hero fighting against evil aliens.