Bully: Scholarship Edition on Steam is pretty cheap, it seems like  your cup of tea since you said Postal 2 and Just Cause 2. But change all that high tech and city environment to a school setting and you got yourself Bully. 

Hmmm if you like old style CoD games,I would recommend CoD WaW,it's my favourite CoD out of all of em,just I don't recommend playing it online much anymore. Though I would also somewhat recommend you Skyrim,just I'm not sure if you'd like it much,but I know I love it! Along with a bunch of other people. Though I mostly love role playing games. If you like tower type defending games,I guess I could recommend you to check out Sanctum 2 at most. Other than that i'm not very sure on what else to recommend. Though you may also like minecraft,it can be pretty fun time to time.

games on pc search it on the internet google on facebook yahoo and there are such many games
or as you like here. vizzed games final fantasy no problem and also mario games or gba games so role playing it could be better
i love role playing games or for free is rpg or may you download it the game

Deus Ex and Half Life are both first person PC gaming classics that everyone should experience.

taterii : sure i'll try to play that game

reptillus max : cool! Well, technically they're two separate games. But yeah.

Robertoman : i highly recommend:
Team fortress 2: a good free to play fps, you can buy stuff and weapons, but it is NOT pay to win AT ALL.
Half-Life: a good fps, has one of the best stories ever, buy it.
counter strike: global offensive: this game needs zero explanation

Here's some I'll suggest for you to try. Most probably not on this site but I'll see if I can think of some from here to add as well. Here we go :
Torchlight 1 & 2, Total War : Shogun 2, Amnesia: The Dark Descent, The Longest Journey, Baldur's Gate 2: Shadows of Amn, Fallout, System Shock, Crysis, Doom, Company of Heroes, Resident Evil, Elder Scrolls, and Silent Hill. Some have multiple games. Just check them out and pick the one you want to try. Hope you try them and like them. Pz out and enjoy. 

You would easily enjoy Fallout 3 and Fallout: New Vegas if you don't mind the rpg aspects. Especially if you get it for the pc. You can watch youtube videos of it if you are not familiar with the game but I HIGHLY advise you give those 2 a shot if you haven't. (hehe shot, get it?)

I have some other great games for you to try out! 

Star Wars: The Force Unleashed
Insurgency
Counter-Strike: Global Offensive 
Need for Speed: Hot Pursuit and/or Underground 2. 

That's it for now. You should definitely check out Need for Speed! But, if you want more action, the other three are great!

Why don't you test out Blocade 3D? It might be a bit hard to get into if you can't get a hold of the controls right away but the game can be a lot of fun. Its kind of like a mixture of Minecraft with a bunch of various multiplayer fighting games.

So many good PC games out there.

Soldier of Fortune
Lego Island
Blood
Team Fortress 2
Fallout Tactics
LoadOut
Fallout 1 and 2
Deus Ex
System Shock 1 and 2
SHOGO: Mobile Armor Division
Claw
Hotline Miami
Carmageddon
Carmageddon II: Carpocalypse Now

I could go on and on and on

Most forgot Space Shooter games. If u like Wing Commander Series try following games. Freespace 2 with Open Source plugin for better graphics and many mods, Freelancer with Crossfire 2.0 Mod, realy good Space trader game and finaly X Series

Also, I know that people have said Half-Life and Portal, but did anyone say Half-Life 2 and Portal 2? The first ones are great, but the second ones are masterpieces. Portal was like Portal 2 but shorter and with less of a story, and while Half-Life 1 was definitely enjoyable, it wasn't as great as people described when I played it for the first time. Maybe because it's so old.
I also agree with The Stanley Parable and especially Team Fortress 2, since it's free to play. Also try Left 4 Dead 2 (the second one has the maps from the first one but with more zombies, weapons and maps and more active servers) or for free games, No More Room in Hell is fun with friends.
Amnesia: The Dark Descent is good if you like horror games. Dead Space too, but its better if you like third-person shooters. Civilization 5 is a great turn-based strategy game. Terraria and Garry's Mod are fun sandbox games that you can waste hours on, especially with friends.
Only other games I can think of is Resident Evil 4 Ultimate HD Edition and Resident Evil HD Remaster, since I love those games so much and they're such classics Hope this gave you some ideas of what to buy!