Zombie Edition is a mod based on original half-life concept, but you will play as a headcrab and, what is more interesting, as a zombie. Zombies can mutate to change their characteristics into three types and every type will have at least six upgrades including using new weapons and abilities.
For further information please check this mod's Official Page.
Remember that other project I was talking about way before? Well, it's up on indiegogo now and needs your support! Back it up, share it everywhere you can and help me create a brand new RPG system!Apr 16, 2013
After a year and a half... it's back! With minor but still nice fixes.Jun 21, 2010
Alas, mod hasn't been properly tested (that happens if you know all the maps by heart), so there were several crucial bugs. Now they are fixed.Nov 22, 2008
Today introducing - new trailer and new screenshots from two maps.Aug 23, 2008