Counter - Strike Source is avaible and Day of Defeat Source will be released next year. But what will happen to the popular Natural Selection mod ? Producer NemesisZero has posted a ( german ) statement in our forums. Here is what he told us ( free translation ) :

A port of Natural Selection to Half - Life 2 is possible. The engine offers a lot of interesting features but the coders hadn't enough time to study the SDK. But before the team decides a change to source ( or not ) Natural Selection 3.0 Final should get released. If the team decides the change, there will be two possibilities : A very basic port which means that there will be as less changes as possible to the game, it should just get work on Source. Or an advanced port which uses the features of the new engine.

But even a basic port could become difficult. An example : The skulk wall - climbing is a hack of the Half - Life engine which simulates a ladder on every wall. Porting such a thing won't become easy and this is just one example... A very basic port will take at least three month.