For games that "don't work" one possible reason is the video card & drivers (usually DirectX) - it doesn't help that it seems to work for everyone else.
More and more games require a recent 3D capable card - but how do you know if your card is "good enough"?
(in laymans terms) A DirectX (or Direct3D) is the way lots of games display graphics, play sounds (among other things) and with each new version, new "tricks" and "capabilities" are added to what is possible by DirectX.
Many newer games take advantage of the "newer tricks" and not only do they need the newer version of the DirectX software to be installed - but they also need a graphics card or chip to be installed that is capable of performing these tricks when requested by the software. (Yes, video cards have a DirectX capable/compliant version also)
For example - Vista comes with DirectX 10 installed, but without the combination of a directX 10 game and a directX 10 card, you won't see any benefits - and most games will fallback to DirectX 9.
If you have a game that needs "DirectX v9.0" to work - just installing the DirectX version 9 software for example, will not necessarily work if you have a "DirectX 7" video card. In fact the game probably will not load, or it may crash, or lock up and freeze, or just run slowly with poorer quality. But chances are excellent it will not be as much fun as you were hoping.
Worth reading - an older (Feb 2005) article that explains DirectX drivers and hardware.
http://www.hardwaresecrets.com/article/95
and
http://www.computerhope.com/directx.htm
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So How do you tell what Video Card you have, and what directX it supports?
Run a copy of GPU-Z from http://www.techpowerup.com/gpuz/
or look up your card (most major cards listed) http://www.techpowerup.com/gpudb/
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What is this "Pixel Shader support" that this game needs
To see if your card is good enough: http://en.wikipedia.org/wiki/Pixel_shader
(The software is still in beta so obviously it doesn't recognise every video card - but getting better all the time).
When posting about problems getting a game running or unexplained crashes when starting, please include some information about your system as it helps trying to find if there are any common factors between different people who might be having similar problems.
How does your system compare to the requirements.
Please provide:
The name of the Game (no pun intended).
Operating System & Version.
Video Card Name/GPU/Memory Size
DirectX Support
Driver Version.
Hopefully with a little more information we will be able to get some people running (or at least determine why they cannot).
For each game - try to reply to existing topics for a particular game - don't start a new topic. Having 20 different topics (one per user) for a single game - only makes it harder for everyone and can require submitting 20 solutions. Let's keep it together.