the foundation of metal gear 2 is preserved to create an absolute masterpiece of a video game - one that expands on MG2's already solid (hold your applause) stealth mechanics by adding additional QOL such as visible enemy FOVs and the much-needed cutback on long-distance backtracking and tedious card management
but most importantly, metal gear solid further explores MG2's focus on the consequences of those who seek to profit off war and the lives that suffer because of it, along with the persistence and importance of individuality and the human connection even in dire circumstances - evidenced by snake's desire to fight for meryl's sake (setting aside the threat of a nuclear war, of course) and his individuality and desire to live for himself at the end of the game contrasting against liquid's goal of following in big boss' footsteps to satisfy his genes telling him to cause problems on purpose
i love the ending split - meryl's ending is, of course, the better outcome as she lives as a direct consequence of snake withstanding ocelot's torture for her sake, but otacon's directly shows the new lease on life he's gained in spite of sniper wolf's death, and is able to encourage snake to move on and not beat himself up over meryl's death knowing her love does not die with her - each ending i think is no better than the other because both of them do a lot for their respective characters

metal gear solid's just fuckin' awesome man, it's true