A mod for Source 2013 which improves the engine and entities to be more capable and stable for mapping and other kinds of modding. It contains new logic entities, new I/O and keyvalues, a custom implementation of VScript, custom shaders with radial fog, countless fixes, and enhanced FGDs all in one big thing. Mappers would create their maps based off of this mod and larger mods with their own unique changes would draw from Mapbase's code and assets.
Custom map compilation tools (vbsp, vvis, vrad) needed to compile Mapbase maps. Slammin' Source works as well.