The new Serious Sam Voice Pack DLC replaces the godlike voice of Elohim with that of Serious Sam as voiced by longtime voice actor John J. Dick and includes a new Serious Sam player model for use in The Talos Principle. The Serious Sam voice pack DLC for The Talos Principle is available on Steam for free until Tuesday, April 7th and then will be available for purchase for $2.99.
http://store.steampowered.com/app/360820/