While the language & feature-set might be a direct competitor to Lua, the license may make it a non-starter for many.<p>Lua: MIT: can be used in closed source software.<p>Jx9: Symisc Public License (basically the Sleepycat license): Very similar to the GPL in that all source code using it must also be open source upon distribution. Otherwise, a license must be acquired at some unknown price to use it in commercial software.