A zombie apocalypse mod, released in 1999 with the name "They Hunger" whose plot begins in certain villages and in towns, infested by a major nest of infected humans including even crabs! Is a very acclaimed mod and I am a big fan of this.
I've played it like a couple of times and the atmosphere isn't so scary at all, unless you have never played it or you're very sensitive/emotional on gore/horror stuff but I can assure you it was a great experience! I have even on my pretty old computer with Windows XP on it!
It's been like a couple of months that I stopped playing on it again, old days were a great time. Here's the link of their main page for those who've never heard of it.
http://www.moddb.com/mods/they-hunger
I've played it like a couple of times and the atmosphere isn't so scary at all, unless you have never played it or you're very sensitive/emotional on gore/horror stuff but I can assure you it was a great experience! I have even on my pretty old computer with Windows XP on it!

It's been like a couple of months that I stopped playing on it again, old days were a great time. Here's the link of their main page for those who've never heard of it.
http://www.moddb.com/mods/they-hunger