This will show you how to play mods like Can Punter, Half-Life 2 Alone Mod and more!

1. First, go into Steam -> Library, then search Source SDK 2013 Singleplayer.
2. After it's done installing, right Source SDK 2013 Singleplayer -> Properties -> Game Versions & Betas -> switch verison to "upcoming"
3. Open File Explorer, find your Steam installation -> steamapps -> sourcemods. Leave the File Explorer open, we will need this later.
4. Download the mod you want from ModDB.
5. Make a new folder in the sourcemods folder, then unzip the contents of the mod you downloaded in that folder.
6. Restart Steam.
7. Yay!