What do you expect for free? Well whatever you expect, you should expect more. This game takes the engine and content you know and love from Half-Life 2, updates it, and dumps you into a whole new narrative with some fun new concepts (like using lights and darkness to manipulate enemies) and battles that should challenge even the most-hardened Half-Life player.
And did I mention it’s free? Go play it, and then go make a donation to the charity that the author recommends on their website. Worth every penny.