it's really easy, just take something that isnt too outlandish and translate it into a movie properly, not just adapt it autistically close like the japanese would do. the western adaptions usually suffer from wanting to adapt and do its own thing at the same time, where its neither fish nor flesh. thats why the japanese ones are better by default, because they dont bother moving away from the material too much. i always bring this up, but look at kill bill vol. 1 for example. it's essentially just a japanese anime/manga/martial arts movie. very derivative and in the core, the story is "just" an americanized lady snowblood. and thats fine, its a basic revenge story on both acounts, the execution matters.

let's say they would actually adapt metal gear solid. what is the core element of the story you would want to adapt? terrorists take over a research facility and take the world hostage and a lone spy has to stop them? this could be either a bond movie or just mission impossible, the only difference is the window dressing, the atmosphere and the style of the whole thing. you dont have to have snake in it, nor liquid, it's about nuclear deterrence and rogue nations or groups having all the power to threaten the world. very topical right now, wouldnt you say?

it's not rocket science, yet they almost always mess it up. i guess they just dont care enough, its just brand recognition.