One of the hardest thing about modern day modding, is that games have basically become "software as a service" and so they are continually being patched and changed. Whilst these changes are almost always for the better, they are usually done with little backwards compatibility in mind.
Whilst this is a minor inconvenience for actively developed mods, many old and classic mods are no longer being worked on as their team has understandably moved onto bigger and better things. Sadly this means many of these mods wind up incompatible with the latest version of the game, until members like malortie step up. Malortie (and others) have worked tirelessly to fix upwards of 50 Goldsource and Source engine mods.
This includes a few of my favorites like Ravenholm, Research and Development, They Hunger and Poke 646. Whether you play Source mods or not, it is the tireless efforts of individuals like malortie that make modding such an amazing community and we encourage everyone to thank him for his work to date. Best of luck malortie and whenever you find the time, you are always welcome here.
I thought I would add onto the end of this post a few quick site updates for everyone. Firstly we have being patching and fixing minor things all over the place. The most recent is an update to the groups system so companies and community groups are more easily found. They are now ordered by most recently updated (not alphabetically) to reward the active groups on the site.
Secondly, work on v5 experimentation has finally begun. Right now we are just exploring ideas, they are all extremely buggy and hypothetical, but once they get a little more polished we plan on inviting our community in to explore them, and help us refine them into something amazing. Busy times ahead!