lengthy post of underrated games incoming!
Spec Ops: The Line
Spec Ops is a criminally underrated 3rd person shooter. One of the good ones. It's about a group of soldiers going into a post-apocalyptic Dubai for a search & rescue mission. It has a pretty deep psychological story, and a really satisfying ending. The shooting mechanics are great and simple, and gameplay is fun. One thing about it is that you actually grow attached to the 2 soldiers you command, which is really nice to see in a shooter.
Sniper Elite v2
This is another 3rd person shooter where you snipe Hitler's balls off and watch them crack, literally. You play as a sniper in World War II, mainly in Germany. It's pretty fucking awesome despite getting mixed and mostly 6/10 reviews, really fun game. There is just something satisfying about shooting a bullet at someone's head and seeing, in X-Ray vision, their skulls crack and the bullet going through their eyes, or their temple breaking, or a bullet that goes right through the heart, etc. It's really fun despite being flawed here and there.
Hotel Dusk: Room 215
Very, very, very criminally underrated and almost not known by anyone. CiNG (the studio behind this game) is a really underrated studio that sadly went bankrupt years ago after releasing the sequel to this game that I'll be writing about shortly. Hotel Dusk is an adventure/point&click game that plays as if you're reading a book, and you would hold the DS as if you're holding a book (sideways). It's about Kyle Hyde, a former police detective who's retired and working as a door to door salesman with the purpose of finding his old partner. It's got really good atmosphere, very believable and relatable characters, good and realistic story, and good puzzles. It's a fantastic DS game, and probably in my top 10 favourite games of all time.
Last Window: Secret of Cape West
This is the sequel to Hotel Dusk, and the game CiNG went bankrupt after releasing. It's got all of Hotel Dusk's features, but with a fresh (and just as good) story.
Tales of Vesperia
This is the pinnacle of the tales series imo, and the best of them. Often overlooked because it's a 360 exclusive and was only released on PS3 in Japan. The gameplay is the same as all other Tales games, with somewhat improved features, and an added new feature called the Skill System. It's simple, you gain Learning Points through battles, and when enough are learned the character learns a new skill, which allows a character to say, for example, attack 4 times instead of 3, or boost defense etc. They can also be found with equipment or weapons. The plot is what sets it away from other Tales games though. It's got your generic saving-the-world Tales plot with a damsel in distress on the side, but it's got twists and turns that really make it interesting and the details are pretty wonderful. It's also got the best set of characters in a Tales game imo.
The Last Story
The Last Story was part of Operation Rainfall, an operation that aimed to make Nintendo localize the 3 Japanese Wii games that didn't get localized because Reggie is a dick, basically. The two other games were Pandora Tower and Xenoblade. The Last Story, being one of the last Wii games (herp a derp) was a really fine game to remember the Wii by. It's got a fucking amazing battle system that's so fucking addicting, even though the story is kinda cliche, but it doesn't matter. The story is about a bunch of mercenaries with one of them (the protagonist) falling in love with a princess, and yeah. It's also directed by Hironobu Sakaguchi which is the godfather of the Final Fantasy series, and I've heard from many that the battle system is similar to that of FF12's, but I don't really know because I never played that. As I said before, the gameplay is really addicting. It's a mixture of strategy, action, and a bit of hack&slash. You control the protagonist while giving commands to the rest of your party to heal/attack/defend etc, and you can perform a couple combos and 'skills' like jumping on the wall to strike an enemy behind its back or something similar. Really underrated, and was overshadowed by Xenoblade. It's biggest flaw though was the fact that it was really easy, wasn't challenging at all sadly except for the final boss.
Then there are things like the 2 console Fire Emblem games on GC & Wii (really underrated, VERY good), Pokemon HeartGold/SoulSilver (the most perfect games I've ever played in my life, totally not overrating), Dishonoured, Far Cry 3, and The Witcher 2. The last 3 might not strike you as underrated, but I feel like they are because they don't get the praise they should be. Dishonoured is a fantastic stealth game that emphasizes on assassination, which is just fucking outright badass and so well-made. You play as an assassin that can stop time, take control of humans/animals, blink (as in warp small distances), etc etc it's just fucking awesome. Far Cry 3 is the only game I played that lets you skin pigs for their leather, go on a boat trip to hunt sharks, and then go back to the jungle to wrestle a tiger for its leather, then sneaking into enemy bases and taking them all out silently to conquer their base. That's so much fun and awesome and just badass. Then there's The Witcher 2, which is in the top 3 of my favourite games of all time, with the other two being Dark Souls and OoT. I'm too lazy to write about it now because it really needs quite a bit of writing, but it's fucking awesome so go play it.