Single Player FPS Campaigns Thread

There are a lot of great free stand-alone first-person shooter mods, such as Free Doom, Xonotic, Nexuiz, Warsow, Alien Arena, Smokin' Guns, Open Arena, and so-on and so-forth. However, with the exception of Free Doom, most of them are Arena Shooters. Arena shooters are great! But from time to time I want to play a regular single-player campaign. I would really like to see more stand-alone first-person shooters with good campaign modes on the Internet. They don't have to be anything fancy, after all, I still like Doom and Quake. But I would like to see more of them. Just a thought. It seems to me that a lot of these arena shooters already have plenty of assets that the creators who made them could use for a campaign driven mode. Again, just a thought.