A single player campaign. You must fight your way to the surface of Black Mesa...
This mod is really awesome. I'm giving it a 9/10. Why? Because it has the old Half-Life feeling that many people felt when they first played the game. The mapping is just gorgeous, believable enviroment. And the difficulty is pretty fair. But it is kind of dissapointing that it's short and the ending creates so many questions, which I hope they will be answered. With that said I'm just going to say that Residual Life, just like its predecessor (Residual Point), is amazing and it's worth the time to play it.