Unknown Worlds, the developer behind Natural Selection 2 (the good game about aliens fighting marines), have done a nice and are giving away their LUA IDE, Decoda, for free in an open source form ...

Natural Selection 2's Lua-based IDE released as open source, use it to make your own game ...

To that end, Marmalade is also integrating both the Lua IDE and Quick’s debug and optimisation options with the Hub, the firm’s go-to tool for managing apps throughout their lifecycle.