ENBSeries was a mod originally made for Grand Theft Auto: San Andreas. It was then expanded to have more versions to work with Half Life 2, Grand Theft Auto: IV and many other games. It would enhance the clients graphics, for example, Motion Blur, Bloom, DOF, reflection etc. What I'm wondering is, would it ever be possible to script this as a client sided mod for special effects like this and someone script this, or would it require an engine change?