In this first version there also are chickens changed to penguins but this is also a test and won't be in later versions. I'm not quite sure anymore, but i think you need optifine for this.
In the first build there is also an Test of the custom sounds. This works with and without optifine. There only is one sound. Its a primitive test.
In the first pack the Zombie Model ist sometimes (50%/50%) my Skin. This is like the Creeper Changes a test of the optifine features and probaply won't be in later versions.
In the first pack you can change the normal Creeper Model to my minecraft Skin if you name the Creeper "Icky". It's just a test and probaply wont be in later versions. It only works with optifine.