What games do you suggest on bad computers?

I was recently thinking, what If u have a really bad PC but still want to play games on it but nothing hits your mind that has loe need on graphics etc. What would be the first game on your mind?

If you can tell me some information about the PC specifications, i can name you a ton of games with pretty nice graphics and good gameplay to play on low spec. PC...

Also, avoid browser games since they are pretty much cpu/ram dependant today thanks to our "very well" optimised browsers... :/

Take an example of ur own thought

Well ill take these specs for a reference:
Dual core Intel/AMD CPU;
1/2 GB ram;
256MB GPU;

Half Life 2 : Episode One and Episode Two;
Mafia: The City of Lost Heaven;
GTA Vice City/San Andreas;
Need for Speed: Underground/ Underground 2/ Most Wanted/ Carbon;
DOOM 3;
F.E.A.R.;
Fahrenheit;
Max Payne: 1 and 2;
Call of Duty 2;
Devil May Cry: 3 and 4;
Prince of Persia: The Two Thrones/ Sands Of Time/ Warrior Within and 4 (2008);
FlatOut 2;
Resident Evil 4 and 5;
Sniper Elite: Art of Victory;
Manhunt 2;
The Elder Scrolls: Morrowind/ Oblivion;
Tomb Raider: Legend/ Underworld;
Bully: Scholarship Edition;
Command & Conquer 3: Tiberium Wars;
Dirt (2007);
The Witcher: Enhanced Edition;
Torchlight 1 and 2;
Burnout Paradise: The Ultimate Box;
Left 4 Dead 1 and 2;
Prey (2006);
Tom Clancy's: Rainbow Six Vegas and Vegas 2/ H.A.W.X. (2009);
Fallout 3;
Dead Space 1 and 2;
Driver San Francisco;
Test Drive Unlimited;
Brothers in Arms: Hells Highway;
Assassin's Creed 1/ 2/ Revelations;
Mass Effect 1 and 2;
Borderlands;
Portal 1 and 2;

Let me know if you need more games!
Cheers