One of the most interesting aspects of the Half life series is it’s wide range of mods and even with Half-Life 2; a free modding system to those who have purchased the HL2 game. I cannot say for sure whether or not Half-life 1 had this amazing component but I’m pretty sure it did not as i have just purchased Half-Life 1 through Steam and no SDK for it has appeared in my tools category unfortunately. I do believe however that a version of hammer exists for HL1 as i have seen it along with many third-party modding tools for HL1. While this may be a Valve product, it is not an SDK all by itself (hammer is just a map editor). I’ve even seen a third-party model viewer for HL1 which would not be necessary if there was one with HL1. The Source SDK has three main components- Hammer editor, Model viewer and Face poser. Face Poser seems to be made for making cut scenes in your mod, but I could be wrong. It allows you to manipulate a characters face and make them talk even, so that’s my logical conclusion- despite having never needed it. The Source SDK also has links to some very helpful programs and places. SoftImage XSI seems very useful if I could get out of my NURBS modeling mindset (I’m proficient at Rhino 3D) and move onto polygons and other programs’ versions of NURBS (nothing seems to have the same NURBS interface as Rhino 3D despite the fact that they also support the same NURBS standards). What I’m talking about is 3D modeling and making your own objects for Half-Life 2 (just felt I needed to clarify as I was throwing around what might seem to some as technical gibberish). It even allows you to edit your own set of the source code, but that requires Microsoft Visual Studio 2003/2004 which i cant afford and cannot seem to find a trial of anymore (they’re on to 2008 which i would download but in 5 years things can change drastically). Anyway, in the meantime I’m happy experimenting with my own maps and trying to figure out if I even want to make something on the large scale.