Lua is the scripting language used in Luxinia. All projects are lua scripts that are executed and everything is controlled using Lua. Since the engine core is doing the expensive calculations, Lua can manage everything around it. All the Demos and examples are scripted using Lua. Using only Lua is just enough for most kind of games - even larger projects can be managed by it. In cases that you are really running out of performance for your gamecode, you could also use lua to execute a DLL that is using just the programming language that you prefer.
Lua scripts are not managed by the resourecsystem, and therefore, directory pathes should be relative to the projectpath or absolute. Since the working directory is always set to the engine's path, it might be necessary to read out the projectpath from Luxinia in order to open files in your projectpath manually using lua.