Originally Posted by Nekomancer
Not really a satisfactory answer
I'm not sure how I can be much clearer.
For every game since the release of L4D, if you are banned in X, the ban only applies to X. It doesn't matter what "engine" they are using.
If you are VAC banned in Modern Warfare 2, the ban applies to *only* Modern Warfare 2. No other games, regardless of "engine", are affected other than Modern Warfare 2.