So the only Metal Gear game I've ever actually played was the 1998 Metal Gear Solid for the PS1 when I was a kid. I've not played a single other game in the series since.
Which ones would you recommend? Would it be better to play them in chronological order to get the full overarching story, or do they work ok independent of one another?
Well, I'd sat 5, phantom pain, has the most solid gameplay loop. It's lots and lots of fun to play and holds up to modern games.
2 and 4 are going to have the most relevant politics. 2 is about memes, information warfare, and the internet as a system of control that can define our perception of reality. 4 is about industrial warfare in the 21st century and how in the pre-Ukraine paradigm the MIC was it's own best customer.
3 is a period drama set during the cold war that has the first appearance of many characters and delves in to themes of betrayal, double cross, and hipocrisy.
1 is the og stealth tactics game. The original will likely seem very basic and dated because it was the game that established the norms of stealth action games as we know him. I don't know how the re-imakes play. 1 has many wonderfully weird, melodramatic characters including the series first appearance of a cyborg ninja, Psycho Mantis reading your mind, and Liquid absolutely devouring the scenary.
If you wanted to follow the story you can play tem in order. I think 5 is the weakest storywise due to development problems, but if you chew on it for a while it has some very interesting things to say about cultural imperialism and what it means to hold on to your identity in the face of cultural imperialism.
For gameplay i'd say go in reverse order as there is a direct evolution and improvement in gameplay in each subsequently game. The original game has an extremely clunky interface and "tank controls" while the last game gives the player enormous freedom and fluidity of motion that allows you to pull off all kinds of crazy stunts and make good use of your gadgets and environments.
I would say that metal gear solid is not an instruction in geopolitics, but rather a catalyst that can lead to an understanding of geopolitics. The game's melodramatic characters, sci-fi goofiness, world spanning conspiracies and deep thematic investigations serve to make geopolitics fantastical and exciting in a way that helps bring you closer to the high level concepts, so that when you put down the controller you can't help but wrestling with the game to understand what the hell Kojima was trying to say and how that relates to politics and history as you understand. Mgs is a fiction that casts light on reality's shadows, helping us contextualize things we knew but didn't understand. That's why it's bizarre, often incomprehensible story is critical; it forces us to impose a coherent narrative on the bizarre chaos of politics and war, challenging us to make sense of the 20th and 21st century instead of telling us a version of events.