A few that come to mind are...
Spec Ops The Line
This game is uniquely written in such a way that makes the player question the morality of what they are doing. It's a full on cognitive dissonance story, where the protagonist's voice actually changes as you progress through a story that has the "hero" doubting his own sanity at times. It also makes good use of unique environmental attacks, and also the need to fight in extreme sand storms. It has tons of replay value, but the hardest mode is brutal, and requires careful consideration of weapons, as they carry over by level.
My surprises were two fold here, I was immediately pulled in by the graphics, weapons, and enemies, but also intimidated by the fast pace and difficulty. There was also some tough platforming I had a hard time getting through. Once I got the hang of how to repeat the glory kill, flame blech, chainsaw combat loop, to keep health, armor and ammo stocked, dominate small areas of a tough battle one at a time, go strait to tough enemies when they spawn, and shortcut platforming, it became Zen-like, even on Nightmare.
Dual surprise here too. Most fall in love with the Grappleshot immediately. It does everything from open up new navigating and climbing possibilities, to allowing you to pulverize enemies with a powerful Shock Punch. The game however has a flip side, in which if you opt to not upgrade anything, you now feel significantly more vulnerable. You have FAR less suit shield strength, no ability to continuously climb or evade fire with the grapple, and no threat sensor to see cloaked enemies (reflections & fog can help). I eventually got to know it well enough to beat Nightmare with no upgrades though, which was both fun and a bit daunting at times. However careful weapon selection can make a huge difference.
The Evil Within
One of my favorite Survival Horror games of all time. At first I thought it too awkward to control and too difficult to sneak up on enemies. I also didn't like the letterbox view, and performance was not smooth. Once those problems were patch fixed, and I studied the game more, I was eventually able to beat it on Akumu mode with no upgrades. The tricks are to stop running once out of sight, THEN hide, as enemies can hear where you ran to, carefully watch for enemies twitching left and right before sneaking up, gather scrap whenever you can (except wall mines on Akumu), use stomps on Alter Ego enemies when prone, approach prone melee weapon enemies from the head when face up, and from the foot when face down, run in large loops when facing enemy waves (so they don't keep spawning) or Ruvik, and make use of those one hit weapons (axe, torch, bottles thrown at wall mines).
Another one of my fave Survival Horror games. It's unique in a couple ways, it has a very good story, characters, and voice acting for this genre, and the Freaks are not actually zombies (won't spoil it for you). They also move fast, but travel slowly in hordes of various sizes. When horde hunting, they roam and feed at 3 different places at night, but hibernate in caves at day. This means you'll often be checking their feeding zones or sleeping spot depending when you look. You also travel via a chopper you can deck out with more off road-like gear, and it serves as a handy save point and ammo cache when near it. Some of the most fun (especially doing jumps with it) and scariest moments are traveling the trails and roads on the bike.
I never thought I would like this game, in fact I kind of went meh when I read the description. This is an "Adventure" game where you play as a stray cat in a post apocalyptic setting, but it's far more than that. There's a lot of peril involved as well with everything from toxic creatures that relentlessly swarm you, to hovering sentinel droids that can quickly find and kill you if spotted. It has a lot of good puzzles and platforming, great graphics, and the story is well told and both sad and humorous at times. Really good varied level design too.