A special Source 2013 mod that helps HL2 level designers make better maps and have a more comfortable experience designing them without changing too much of the game itself. Mapbase includes 50+ new entities (not counting filters or engine ports), hundreds of new I/O/KV (Inputs/Outputs/Keyvalues), heavily reworked FGDs, and a few big surprises. 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.
hl2_gamerules is supposed to be Half-Life 2's equivalent of entities like tf_gamerules. It can control various HL2-related settings, like the default citizen type (the type used for "Default"), the legacy flashlight (HL2/EP1 flashlight as opposed to EP2 flashlight), or even whether the player's squad automatically starts following the player again. Friendly fire override can be found as its own global state.