Have you looked at the indie game Natural Selection 2 by Unknown Worlds? It seems to have a similar modding structure to Garry’s Mod whereas (Correct me if I’m wrong) the C++ engine is manipulated via various lua scripts. Do you find this practice more appealing only to indie developers? In a technical sense how would you change Garry’s Mod if you had the time/money etc.?

Having a scripting language makes everything easier.. and more moddable.

If I could do it again I’d use javascript instead of Lua.