Far Cry originally was from CryTek and while linear did allow you some relative, especially for the time, freedom for much of the game to tackle enemies however you saw fit. Be it sniping them from afar, going in just blasting, or driving a Jeep over top of them. Crysis basically built off of this where the game is linear but is a bunch of sandbox areas stuck together.
Far Cry stayed as a Ubisoft property though. And with 2 they basically turned it into a crazy open-world FPS where this freedom was truly amped up. 2 had things like propagating fire and weather and day/night cycle that you could use against enemies. (There'd be guys inside during storms at night rather than outside, etc., they'd run from the fire and get alarmed overall, etc.) 3 amped this up and especially into stealth. 4's addition is mainly the location allowing for lots more stuff with the mountains and height being more of a factor than in earlier games. (Also it has a hilarious twist available.)
And then there's 3: Blood Dragon which is all of this but set in a 1980s era low budget dystopian sci-fi action flick. I guess Primal is the same concepts but set in the Stone Age, I haven't played it.