How different is the leak engine in comparison to release day Source?

[wiredonaccela]

A question thats been bugging me for a while is just how different the build of Source seen in the leak is to the 2004 release branch of Source, i’ve noticed some differences but i’ve been wondering just how different the two are exactly from each other.

[nigar123nigar]

half life 2 beta used a modified version of the gold source(used for half life 1)
it contained a lot of half life 1 sounds and models. The models were tweaked to look a better, as for the sounds, they remained the same. In the half life 2 beta(not the mega build) there was only one way to look up and down page down and page up. So that answers your question.

[Витой]

In the half life 2 beta(not the mega build) there was only one way to look up and down page down and page up. So that answers your question.

Nope, you just had to enable mouse look in game's settings.