[clug] moddable ipad games?

[jm]

A friend's son has an interest in learning about games programming but 
doesn't have a programming back ground. His about 14 and has the use of 
an ipad. With Lua being a common embedded language in games I was 
wondering if there were any games out there where you can mod the game 
in situ. This might be more of interest to him that reading books and 
doing programming exercises at this stage. The idea being to use this as 
a lead in to more formal learning. I've suggested one or two learn to 
code sites so far. Anyone know of anything along these lines or have any 
other good ideas I can put forward?

Jeff.