Metamod is a plugin/DLL manager that sits between the Half-Life Engine and an HL Game mod, allowing the dynamic loading/unloading of mod-like DLL plugins to add functionality to the HL server or game mod. Metamod-P is enhanced version of Metamod. It has dynamic link-entities and automatic detection of Mod DLL and other improvement to allow it work with future Half-Life Engine updates and new Mods and updates.
enginecallback.h is missing
#define GETPLAYERAUTHID (*g_engfuncs.pfnGetPlayerAuthId)See https://github.com/alliedmodders/hlsdk/blob/master/dlls/enginecallback.hThe current define
#define GETPLAYERWONID (*g_engfuncs.pfnGetPlayerWONId)is not up to date anymore.