Originalfatass
My personal favorite of the Stalker games due to the faction war system. It's an improvement over Shadow of Chernobyl in most areas, except the gunplay. That was transitioned into a system where it encourages you to stick with a single gun and upgrade it as opposed to having to trade guns out as they wear out.
2014
2010
The first of the Metro games, and a spiritual successor to S.T.A.L.K.E.R.. Overall, it's a solid game, that's a great example of eurojank. It loosely follows the novel of the same name, but cuts out some of the longer sections. The atmosphere, and setting are phenomenal, though the Redux version is overall going to be the better experience.
2014
2013
2019
1998
What many consider the best MGS title, and rightfully so. It's an amazing story, with amazing gameplay. As the first point in the entirety of the Metal Gear timeline, it retcons shockingly few things, but does explain a lot about everyone's favorite mustache, and revolver twirling spy; Revolver Ocelot.