If you haven’t played Half-Life or any of its iterations yet, Steam has a special weekend deal. Everything related to Half-Life, including 1, 2, the Episodic content, Team Fortress Classic, and more are all 66 percent off, with each game costing less than six bucks. Or if you want a bundle, you can get the Half-Life complete package at $16.99.

By now, there really isn’t any excuse to pick up anything in the deal. Even though these games are fairly old, all of them remain as great first-person shooters. The first game was many’s first taste of actually being a character (and begin the destruction of research facility, but that’s something else) instead of controlling one. The second was one of the first to implement a physics-based engine well into first-person shooter gameplay, not to mention the Gravity Gun. Its quite a bit of content (or a good history lesson) for under $20. Check out all the games included in the deal at Steam’s website.