Steam Co-Op from Sven
The team behind Sven Co-op, a Half-Life mod that's been under development for ¾'s of my lifetime, have announced that the 4.8 version of the game would likely be the final version. Why? Because it's coming to Steam.
The team has not stopped development of the project. What they've done is broker a deal with Valve to release a stand-alone version. Valve have allowed the Sven team to access the GoldSrc engine code so that they may make their own version of the engine for the best possible co-op experience. On their list of improvements to make are larger, more detailed maps as well as a better Hammer level editor.
When the game is complete it will be made available for free for all Steam users with no purchase of the first Half-Life necessary (which is pretty rad). But, that said, there is currently no word on a set release date. Considering the mods been under development for 15 years already we may be waiting a little while longer before it eventually appears on Steam. So, for now, check out the official announcement on the Sven Co-op forum here.