It's a series of stealth/shooting games. You play as different characters in different games but just about all of them are or were called Snake. Gameplay usually consists of sneaking around a large, connected world going from point to point as the story dictates.
It's kinda like a stealth Metroid in that you're free to go wherever you want most of the time, there are lots of secrets hidden around, and you often have to find certain items to progress. The story takes place in a slightly futuristic world (some, MGSV included, take place in the past though) that's otherwise supposed to mirror our own. It's very complex and any given game will have SEVERAL major plot twists.
As such it's pretty tough to summarize and nearly impossible to do so without spoiling everything. Sufice to say you're usually a guy tasked with infiltrating some terrorists'/extremists' base and stopping them from launching a nuke. If you don't mind spoilers you can find full summaries on youtube or the Metal Gear Wiki.
Expect a lot of long cutscenes and talking. Also expect to suspend your disbelief a lot. Complex as it is, there are a lot of parts that make next to no sense.
And there are a lot of really cool secrets/easter eggs in most games, so be on the lookout.
It is a very cinematic, story-heavy series. Lots of plot twists and if you want to understand the story of TPP, there are four other games that come before it and you'll miss a lot of foreshadowing/flashforwards to the four games after it.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.