Far Cry is basically Half-Life reiterated in a tropical island setting. And instead of the game world being mostly alien beasties with the occasional well-scripted soldier attack, it's mostly soldiers with the occasional mutant beastie for flavoring.
I hesitate to call the soldiers "well-scripted" because even though that's an intent and a marketing point of the game, I found them to be pretty dumb across the board. About the only intelligent thing they do is to try to flank you when in numbers, but they don't actually coordinate the action in any way, so it's usually easy to mop up a group coming from one side then be in wait for the group coming from the other. Put them in corridors and tight spaces and they do all sorts of the stereotypical FPS stuff like spotting you and then following you through a doorway where you're waiting in ambush, and etc. Going into any kind of foliage cover also confuses the hell out of them, they'll immediately stop shooting and lose track of you even if it's like the only bush for 500 yards around.
So you play as Hawaiian Shirt Man, some guy who was out tooling around the Caribbean with a bikini babe when a storm came up and wrecked the boat. You get a confused flashback of being chased by mutant wild boars and then a bunch of mercs with machine guns, then the game deposits you in someone's basement with no weapons. You soon find a mysterious radio that connects you to Morgan Freeman, however, who gives you intel on the mercs and objectives to pick your way through them, find the captured Bikini Babe, and get off the island. It turns out Hawaiian Shirt Man is actually some sort of professional bodyguard and Bikini Babe is the reporter he was escorting to investigate the mysterious island that some scientist has been doing reclusive research on, but none of this is volunteered in-game until you've played through a few chapters, so initially it looks like you're doing the fastest transformation from average schmo to Rambo John J since Lara in the Tomb Raider reboot.
The level structure is a little different from your usual FPS. The game uses an auto-save checkpoint system rather than allowing you to save anywhere, for starters, and it breaks the game world up into distinct self-contained "maps" that you progress through in a linear order (in the old-school Doom sort of style). But those maps can be pretty damn huge and far-ranging, giving you tons of open terrain to work with and multiple ways to approach enemy positions. Even with body armor, you can't take more than a few shots, so charging everyone Duke Nukem style usually ends badly for you. Using foliage cover to approach an enemy position and picking them off from around the edges / shooting propane tanks they happen to conveniently be hanging out by is more the order of the day here.
The game is clearly going for an Apocalypse Now sort of vibe from the jump, but over-the-top voice acting and cheesy dialogue sinks any literary pretensions it might have (Spec Ops: The Line this ain't). It's so overdone it enters that lovable cheesy territory that a lot of Dreamcast games did, though. In fact, aside from the fact that it looks nicer than anything on the system save Shenmue, this game would have been totally at home in the Dreamcast lineup. It's like if the director of Blue Stinger decided to do an interpretation of Heart of Darkness.
Though the guard AI and teamwork is a bit overblown, there are still some pretty impressive qualities here for a 2004 release. Developer Crytek created their own engine from scratch for this game and it's pretty well-composed. Draw distances are greater than usual for the time, there's an impressive array of vegetation, and in general the island settings look really nice and are believably detailed and well-thought-out. There's a couple of "killer app" toys, too. You get magic binoculars that can not only zoom a fairly impressive distance, but also mark mercs (since they are all apparently implanted with radio chips) and use a directional mic to listen in on their conversations. There's also vehicles. Dune buggies, jeeps and even a few different types of boats, which not only all handle pretty well but sometimes come equipped with multiple weapon types. And the enemies will hop in and drive them as well.
"Guards come runnin' for the great taste of lead!"
There's some sort of online multiplayer component, but I don't know if it even works anymore. With these old Ubisoft games you have to be happy if you can even get the single-player offline up and running. I do think Far Cry is worth a run, though. The whole series is like this odd evolutionary branch that FPS *could* have gone in instead of the tight-corridors, heavily-scripted Dudebro military spectacles that we got instead. This first one isn't advanced enough to allow the glorious chaos of the later games like unleashing tigers on enemy camps and such, but it's good enough to be worth playing and a good starting point for getting into the series. Especially for the pittance you can get it for these days.