Valve's Source engine is starting to show its age, despite frequent upgrades. That doesn't mean it's worth throwing out, though. Even though we may never see Half-Life 3 in our lifetimes, there's still plenty of awesome stuff going on in the Source sandbox to keep us occupied. Enterprising modders have used the technology to create a flabbergasting variety of cool stuff. We talked about the Best Game Mods in general, but now we'll focus on Source alone, because it more than deserves the attention. In this article, we'll share eleven of the most ambitious Source mods ever released and tell you where to get them.