A slight request than explaining this game in this section, but i had put a fair amount of hours into this game in the past, and i found out ( after the client broke and servers broke years ago ) a fix was released earlier this year 
Maybe some people on here have played it in the past, but i would strongly suggest giving it ago. It requires HL2: Deathmatch and SDK 2006 and the following mod!
http://178.32.57.113/SFFixed_0.3b.exe
It was and i believe to be a real fun mod, and as a quick explanation of the game; It is a mix between garrysmod and any hl2 fps game. For the first 8~ minutes, you build and secure your flag, making sure you can get out and in ( or even having your own design to capture the flag ). Then for the next 10 minutes you fight with various different classes to choose from.
For those willing to give it a try, when you install the mod it may ask for the location to install ( Steam\SteamApps\sourcemods\sourceforts ) also make sure you use the Complete install option.
Will be playing this evening at some point if anyone is up to tag along, a server is up and running ;>
Full Install Instructions ( as sourcemods can be a pain )
> Install / Update HL2 Deathmatch
> Install ( the Tool ) SDK 2006
> Run HL2 Deathmatch at least once ( quit from the menu )
> Install http://178.32.57.113/SFFixed_0.3b.exe using Complete install option and the path to your sourcemod folder ( Steam\SteamApps\sourcemods\sourceforts ) with sourceforts added to the path.
if you have issues just msg me ;>
Will schedule a few games this saturday from 4:00pm (GMT+0)
