Postal 2 - Funny as hell
Portal 2 - Good story and hard puzzles but the community can make them alot harder
Team Fortress 2 - Good casual FPS game (I suggest trying MVM Mann vs machine)
Don't Starve - A survival game with no instructions
Cry of Fear - Horror, good story, fun multiplayer
Killing Floor - Fun addictive multiplayer with multiple classes to choose from
Planet Side 2 - A LARGE RPG FPS game. Huge maps, multiple classes, 3 factions to choose from.

1) Metro 2033.

It's an adventure game something like the RPG Fallout 3 (which is also worth a good look or twelve) but it takes place in Russia. I can't say too very much about it without spoiling a lot, but its story is exceptional and the mood of the game as a whole is very very good.

Mechanically, the game is unique (or at least fresh) with its ability to portray ammo scarcity, radiation and overall vulnerability in a world where one would naturally be endangered and eager to avoid a fight.

One of my favorite games to come out in the past 10 years.

2) Corpse Party

This game is a psychological horror game with a setup that is something like Pokemon. Top-down controls, and pixellated. Nonetheless, this game is probably 8-12 hours of gameplay and is legitimately unnerving at times. Puzzles as atmosphere laden as the pictures in those "Stories to read in the dark" you used to read when you were younger.

You may have to risk getting an emulator for it, but it is a very solid grip on horror that I've not seen before or since from a pixellated title.

3) Styx: Master of Shadow

This game is more of a sneak-to-win sort of game, but it excels where most don't. In this game, you are rewarded for playing it patient, and are actively hurt for being too careless. With an AI that fits the mood, with some hiccups here and there, you'll be treated to a game where you regularly throttle sleeping guards, shiv the helpless and cause general (under the table) havoc.

Think if LOTR and Splinter Cell had a baby, and it was DIFFICULT.

4) Alien Swarm

Good for a stand alone game, and even better with 3 friends, you play as a squad of Hazmat-Marines sent into a derelict ship in space that sent a number of distress signals and then went into radio silence. The game is predictable, and doesn't pretend to be oriented around the story.

Top-down shoot 'em up style game something in the vein of Smash TV or the Nazi Zombies minigame.

Grab some friends and enjoy blasting away at the filthy xenos crawling about the ship (or if you're feeling like a real pro at the game, play on the difficulty named "Brutal" with the "Onslaught" mode on. This makes the game so hard that you will go into laughing fits from how quickly you die, rather than the panics of surviving close calls, as is the case with the harder difficulties anyway).

A 8/10 partygame pick.

5) Team Fortress 2

A shooter game that needs no introduction in the realms of internet gaming. Class oriented objective-based gaming hosting two teams (RED and BLU) with a hidden storyline thrown in.

If you enjoyed the game modes from Halo, and the difficulty of dying a million times to people on Counter Strike, then you're probably going to have some familiar love-hate relationship with TF2 somewhere down the line.

The learning curve is steep, but if you stick it out long enough to learn how all the classes work (and why Engineer players are the most boring people in the whole universe) then you're down for a fun time. You can even bring your friends to die alongside you (because I'm not even exaggerating there are players playing one class that they've not stopped-playing since 2009).

RPG: Baldur's Gate 2 (nevermind the first one); Fallout 1&2&New Vegas (not that 3 can't be fun but it's Oblivion with guns, not Fallout); Planescape: Torment (if you drool over dialogue trees).
FPS: STALKER! (with graphic mods at least).
Stealth: Deus Ex HR; Splinter Cell (recommend Chaos Theory); Dishonored.
Strategy: Europa Universalis (say goodbye to your life), you need to go through a lot of tutorials to have a good understanding of the game but it's worth it.

I gotta say, I love the Fallout series. "Mini Metro" is great for a quick, casual game. is relatively new on Steam (it used to be PlayStation 3 exclusive). Um... Star Wars:  KotOR I and II. Mass Effect I and II. Project Zomboid, Mount & Blade:  Warband, and Torchlight are all wonderful RPGs, though I guess PZ is more of a sim at times. For musical games, Drive Any Track and Melody's Escape are my go-tos, but I'm thinking about picking up Beat Hazard, too. If you're into visual novels, I highly recommend planetarian ~the reverie of a little planet~. It's absolutely heart-wrenching. A great Early-Access shooter is Interstellar Marines, though co-op gets a little... terrifying. Killing Floor (2) is also oodles of fun. I recommend Portal and Portal 2 for puzzle games. Burnout Paradise is a great racing game. Dynasty Warriors 8 Empires is fun, but it's glitchy on PC, so it's a bit of a gamble. DW8XL isn't as bad. A good JRPG is Hyperdimension Neptunia Re;Births 1 and 2. They're fairly light-hearted and poke fun at the gaming world all the time. I have plenty more suggestions, but it feels like I'm going on a rant at this point.

Totally random: World of Goo, BaboViolent2, Peggle, Hard truck Apocalypse, Crashday!

i recommend:
-counter-strike: global offensive if you're into high level of competitive play
-dark souls if you have a controller. very difficult and punishing but its very rewarding.
-dota 2 or heroes of the storm for MOBAS (multiplayer online battle arena) for a casual and competitive play.
-TF2 for a free casual fps game with its own economy
-insurgency for a realistic fps set in a modern time. (terrorists vs us marines) 
-rust/arma series for a big open online fps world with tones of things to do so it'll keep you playing. (better with friends)



  

Go ahead and play some Team Fortress 2. You will love it.

Try League of Legends It's not for everyone, and while it has a pretty large learning curve, it's pretty fun once you get the general idea of the game, and it has unlimited "replay" value.

Go to: itch.io

Seriously, thousands of quality, free games you can download, handcrafted by indie devs. I highly recommend Roguelight as your first one.

I played Borderlands 2 on the PS3, and while I still thought it was great, I wasn't all that into it.

Now I'm investing in the PC version... hm.

Halo CE is a classic.

 Don't play PC games, they make you stoopid.