"Installing" Mapbase is basically just like any other Source mod, except there's three folders instead of one. To install Mapbase, follow these instructions:
- Install Source SDK Base 2013 Singleplayer and set the branch to -upcoming if you haven<65>t already.
- Extract mapbase_episodic, mapbase_hl2, and mapbase_shared from the .zip archive downloaded earlier to your <20>SteamApps/sourcemods<64> directory.
- Restart Steam.
You should now have <20>Mapbase - Episodic<69> and <20>Mapbase - HL2<4C> in your Steam library. If not, make sure you're using the same drive Steam is installed on and ensure that you extracted the folders correctly. (e.g. "SteamApps/sourcemods/mapbase_shared")
If you have followed all instructions correctly, Mapbase should be fully playable at this point. mapbase_episodic is for the HL2 episodes, mapbase_hl2 is for the original HL2, and mapbase_shared just contains miscellaneous content not unique to Half-Life 2.
Using Mapbase in Hammer is a bit more complicated and steps for that can be found here:
