Zombie Edition is a mod based on the original Half-Life concept, but you will play as a headcrab and, what is more interesting, as a zombie. Zombies can mutate into three types to change their characteristics and each type will have at least six upgrades, including new weapons and abilities.
For further information please check this mod's FAQ.
Q: Can you make this mod for hl2/ep1/ep2/hl:s?
Q: Will it be possible to play as a gonome?
Q: Can you add multiplayer?
Q: WIll there be a sequel?
A: No way.
Q: Can I download it?
Q: How do I install it?
A: Check the instructions here (specifically, check the description, click "+read more").
Q: Do I need the original Half-Life to play this mod?
A: Yes, duh. Buy it, by this point it's dirt-cheap on Steam.
Q: Can I play this mod using Half-Life: Source?
Q: Will you release this mod through Steam Greenlight?
A: While I'd like to do so, submitting a game to Steam Greenlight is not free and I do not currently have any money to spare.
Q: How do I buy upgrades/zombify someone/eat bodies etc.?
A: This tutorial has all the answers. In short (by default), TAB is the upgrade menu, R is jumping off a host body as a headcrab, 1-5 are weapon categories, E is eating bodies (try to aim at the center of mass, be as close as you can), special ability keys are Z and X (check your controls settings to see if it is so).
Q: I am epileptic/annoyed by the zombification images. Can I disable them?
A: Yes! Type "ze_galluc 0" in your console (console must be enabled) without quotation marks. "ze_galluc 1" brings them back.
Q: My screen is black (and I'm not in the process of zombifying someone). How do I fix it?
A: Use OpenGL or Direct3D setting in your graphical settings menu.
Q: I'm stuck (not literally, but I can't progress)! What do I do?
A: If you are sure that there is absolutely no way to progress (sometimes it can be not immediately obvious, try looking for hidden alternative paths), then too bad for you. In this game you can, sometimes, end in a no-win situation by making wrong decisions.
Q: AI is stupid. Can you fix that?
Q: I can hear the sound of footsteps even though I am supposed to be a headcrab/silent. Can you fix that?
A: Surprisingly, no. But the enemies won't hear you.
Q: Can you play through the original HL/OF/BS with this mod?
A: Hypothetically you can play through the original Half-Life by just using the "map c0a0" command in the console, but I wouldn't recommend it. Mods like Blue Shift which do not change the code of the game and just add new maps could be played by copying all their resources in the zombie folder, mods like Opposing Force, which do change the code, can not.
Q: I want to play this mod on Linux and I'm having issues. What should I do?
A: Sadly, I don't know. I don't have any version of Linux myself, so I can't test anything. If anyone have succesfully installed and played through this mod on Linux, please leave a comment describing how to install it and workarounds for any encountered problems and I'll include it here.
Q: Will you make any more maps?
A: I doubt anyone from the team will, though anyone is certainly permitted to do so, you included! The mod includes a folder called "devkit" which contains a .fgd file for this mod so you can use it in Valve Hammer Editor.
Q: I liked this mod very much! How can I show my appreciation? A: Well, tell your friends about it. The more people know about it, the better! Now, if you want to provide something more material, you can also donate, though, of course, you are under no obligation to do so and there are no hidden bonuses received through such action.